• Users Online: 57
  • Print this page
  • Email this page

Table of Contents
Year : 2019  |  Volume : 11  |  Issue : 2  |  Page : 61-66

Clinicopathologic study of colonic polyps in South Western Nigeria

1 Department of Medicine, College of Medicine, University of Ibadan, University College Hospital, Ibadan, Nigeria
2 Department of Pathology, College of Medicine, University of Ibadan, University College Hospital, Ibadan, Nigeria

Date of Submission25-Feb-2019
Date of Decision31-Jul-2019
Date of Acceptance10-Aug-2019
Date of Web Publication22-May-2020

Correspondence Address:
Dr. Adegboyega Akere
Department of Medicine, College of Medicine, University of Ibadan, University College Hospital, PMB 5116, Ibadan
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/NJGH.NJGH_5_20

Rights and Permissions

Background and Aim: Colorectal cancer (CRC) is known to be a major cause of morbidity and mortality worldwide. It is believed that CRC develops from adenomas or benign adenomatous polyps. Information concerning this premalignant condition in Nigeria is still relatively scarce. The aim of this study was to describe the clinicopathologic features of colorectal polyps seen in patients who had colonoscopy at the University College Hospital, Ibadan, Nigeria.
Patients and Methods: This was a descriptive cross-sectional study carried out at the Endoscopy Unit of the University College Hospital, Ibadan, Nigeria. Colonoscopy was performed on the patients after bowel preparation. Polyps were characterized by their colonic location, size in millimeter, and histopathological diagnosis. The data were analyzed using SPSS version 17.0.
Results: The patients comprised 65 (58.0%) males and 47 (42.0%) females. The mean age was 60 ± 12.5 years, with majority being in the age range of 51–60 years. The most common indication for colonoscopy was hematochezia. The location of the polyps was as follows: 41 (36.6%) in the rectum, 30 (26.8%) in the sigmoid colon, and 22 (19.6%) each in the transverse and descending colon. In 51 (45.5%) patients, polyps were <5 mm in size; 5–10 mm in 48 (42.9%) patients; and >10 mm in 13 (11.6%) patients. The most frequent histological diagnosis was adenomatous polyp.
Conclusion: Polyps were found more commonly in males and in individuals aged 50 years and above. The most common location is the rectosigmoid colon, and the polyps are majorly adenomatous. Our findings suggest the need for colonoscopy service to be made more widely available across the country so as to contribute to reduction in CRC incidence among Nigerians.

Keywords: Adenomatous, colonic polyps, diminutive polyps, Nigeria

How to cite this article:
Akere A, Ezenkwa US, Oluwasola AO. Clinicopathologic study of colonic polyps in South Western Nigeria. Niger J Gastroenterol Hepatol 2019;11:61-6

How to cite this URL:
Akere A, Ezenkwa US, Oluwasola AO. Clinicopathologic study of colonic polyps in South Western Nigeria. Niger J Gastroenterol Hepatol [serial online] 2019 [cited 2022 Jan 17];11:61-6. Available from: https://www.njghonweb.org/text.asp?2019/11/2/61/284717

  Introduction Top

Colorectal cancer (CRC) is known to be a major cause of morbidity and mortality worldwide.[1],[2] More than 9% of all cancer incidences are due to CRC, and it is the fourth most common cause of deaths from cancer.[3],[4] It is believed that CRC develops from adenomatous polyps.[5] This process, which is known as adenoma-carcinoma sequence, is a multistep process which can take up to 10–15 years to develop.[6] Adenomas are believed to contain dysplastic epithelium which are believed to result from mutations in different genes.[7] It has been demonstrated that endoscopic polypectomy reduced both the incidence and mortality of CRC.[8],[9]

Most data concerning adenomatous polyps and CRC screening were mainly from Western Europe and the United States.[10],[11] Colonic polyps were believed to be rare in Africa, and this was also suggested to account for the low incidence of CRC in this region.[12],[13] However, the incidence of CRC in sub-Saharan Africa has been observed to be on the rise.[14],[15] It is possible that the increasing availability of colonoscopy services at some centers has made early diagnosis possible. Not only this, colonoscopy has also made early detection and removal of polyps possible.

There are few publications on polyps in Nigeria,[16],[17] but there has not been any such previous publication from our center which is a major referral tertiary health facility in the country. The aim of this study was to describe the clinicopathologic features of polyps seen in patients who had colonoscopy at the University College Hospital, Ibadan, Nigeria.

  Patients and Methods Top

This was a descriptive, cross-sectional study carried out at the Endoscopy Unit of the University College Hospital, Ibadan, Nigeria. All consecutive patients who gave consent were recruited into the study. Patients with previous hemicolectomy and those in whom cecal intubation was not achieved were excluded from the study. In this study, procedures were followed in accordance with the revised Helsinki Declaration (2013).

All the patients had bowel preparation which consisted of 3 days of liquid diet, bisacodyl tablets 20–30 mg daily, as well as oral normal saline 2 L in the morning and evening a day before the procedure, and another 2 L early in the morning of the day of the procedure. Shortly before the procedure, patients were administered intravenous midazolam 2.5–5 mg and pentazocine 15–30 mg, as required. Colonoscopy was performed using an Olympus Exera III Videocolonoscope (CF HQ190L, Olympus, Southend-on-Sea, UK). The vital signs of the patients were monitored pre-, intra-, and post-procedure using Multiparameter Monitor (Marathon Z, Health-care Equipment and Supplies Co. Ltd., Staines, Surrey, UK).

Cecal intubation, defined as visualization of the medial wall of the caecum (when the appendiceal orifice and the ileocecal valve were identified), was ensured in all the patients. Thorough examination of the colon was also carried out on withdrawal of the scope so as to detect any polyp which was missed during insertion.

Polyps, when detected, were characterized by their anatomical location in the colon; the size was estimated in millimeter, using the fully opened cup of the biopsy forceps (the fully opened cups of the biopsy forceps was 5 mm in size). The appearance of the polyp, whether sessile or pedunculated, was also documented. The polyps were removed using either cold biopsy forceps or hot polypectomy snare depending on the size. The specimens were sent to the histopathology department and were processed and reported by a consultant pathologist.

The data were analyzed using SPSS version 17.0 (SPSS Inc., Chicago, IL, USA). Means were computed for continuous variables, whereas categorical variables were analyzed using percentages. P < 0.05 was considered statistically significant.

  Results Top

The data of 112 patients were analyzed, comprising 65 (58.0%) males and 47 (42.0%) females, giving a male:female ratio of 1.4:1. The mean age of the patients was 60 ± 12.5 years, with a range of 11–88 years. The mean age of the males (58.5 ± 13.3 years) was slightly lower than that of the females (62.0 ± 11.1 years), but there was no statistically significant difference between the mean ages (P = 0.14)

Majority of the patients were within the age range of 51–60 years [Figure 1]. The most common indications for colonoscopy were hematochezia, constipation, abdominal pain, and probable abdominal mass in 44 (39.3%), 20 (17.9%), 16 (14.3%), and 11 (9.8%) patients, respectively. Other indications are as shown in [Table 1].
Figure 1: Age groups of the patients

Click here to view
Table 1: Indications for colonoscopy in the patients

Click here to view

In terms of location of the polyps, 83 (74.1%) of the patients had polyps in only one part of the colon, while only one (0.9%) patient had pancolonic involvement, as depicted in [Figure 2]. The colonic location of the polyps was as follows: 41 (36.6%) in the rectum, 30 (26.8%) in the sigmoid colon, and 22 (19.6%) each in the transverse and descending colon [Figure 3].
Figure 2: Number of locations of polyps in the colon

Click here to view
Figure 3: Colonic location of the polyps

Click here to view

The results showed that in 51 (45.5%) patients, the average size of the polyps was <5 mm in size; 5–10 mm in 48 (42.9%) patients; and >10 mm in 13 (11.6%) patients [Figure 4]. In 96 (85.7%) patients, the polyps were sessile, while pedunculated polyps were seen in 24 (21.4%) patients.
Figure 4: Sizes of the polyps

Click here to view

From the results, the most common histological diagnoses for all the polyps were found to be adenomatous polyp, inflammatory polyp, hyperplastic polyp, and adenocarcinoma which were reported in 46 (41.0%), 42 (37.5%), 13 (11.6%), and 5 (4.5%) patients, respectively [Table 2]. The histological diagnoses in patients with diminutive polyps (polyps <5 mm in size) are presented in [Table 3].
Table 2: Histology of all the polyps

Click here to view
Table 3: Histology of diminutive polyps

Click here to view

Out of the 19 patients who had polyps in two different locations in the colon, four of them had different histology of the polyps in each of the locations. In one of the patients, the histology of the polyp in one location was actually an adenocarcinoma, whereas in the other location, it was hyperplastic polyp.

  Discussion Top

In this study, there was a male predominance. This was also the observation of Oluyemi et al.[16] in Lagos and Alatise et al.[17] in Ile-Ife, both in the same southwest region of the country. Other studies have also shown higher prevalence of colorectal polyps in males than in females.[18],[19] This observation could be related to the male predominance of CRC. Similarly, in a meta-analysis by Nguyen et al.,[20] more males were found to have adenomas with advanced histology. The possible explanations for the low rate of polyps seen in females are reduced secondary bile acid production, reduced serum levels of insulin-like growth factors, and the protective role of estrogen in women.[18],[21],[22],[23],[24]

The mean age (60 ± 12.5 years) of our patients was higher than that reported in similar studies conducted in the same southwest region of the country.[16],[17] However, it was slightly lower than that observed by Laird-Fick et al.[25] in the United States. This was not surprising because their study was mainly among older adults.

We observed in this study that the mean age of the males was lower than that of the females. This was also reported in some CRC screening studies, where adenomas were found to occur a few years earlier in males than in females.[26],[27] This observation might suggest the need to start CRC screening at an earlier age in males, and this had been suggested by some authors,[27],[28] although current guidelines on CRC screening did not recommend this.

In this study, hematochezia was the most common presentation in our patients, which was again similar to the findings of Oluyemi et al.[16] and Alatise et al.[17] among their patients. In addition, in a study by Segal et al.[13] among Black and White patients in South Africa, hematochezia was the most common presentation in both groups. Although most patients with colonic polyps are asymptomatic or may have nonspecific intestinal symptoms, the most common presentation is intermittent overt or occult rectal bleeding.[29] Other symptoms may include diarrhea, constipation, and flatulence, as observed in some of our patients. It has also been reported that patients with villous adenomas could present with an uncommon syndrome of secretory diarrhea with life-threatening electrolyte and fluid loss.[30]

In terms of anatomic location, the polyps were located in the left colon in 85% of the patients, and out of this, the most common location was the rectosigmoid colon. Again, this was similarly reported by Oluyemi et al.[16] and Alatise et al.[17] This finding correlates with the observed anatomic distribution of CRC observed in some studies.[13],[31],[32],[33] This observation might suggest that sigmoidoscopy as a screening tool for CRC was adequate. The fact that some polyps were detected in the right colon gives full colonoscopy an advantage and makes it a better screening tool for CRC over sigmoidoscopy, although the latter is cost-effective and easier and faster to perform. Studies have also shown that up to 50% of neoplastic polyps and CRC were missed by flexible sigmoidoscopy.[34],[35],[36],[37] However, in contrast to our finding, Laird-Fick et al.[25] and Visovan et al.[38] reported predominantly right-sided polyps. The same observation was reported by Khalid et al.[39] and Cheng et al.[40] These latter studies were, however, conducted in non-Africans.

Our study showed that majority of our patients had diminutive polyps, that is, polyps with size <5 mm. These polyps have been said to be commonly encountered during colonoscopy, and are of little clinical or biologic significance.[29] However, some studies have found about 30%–50% of these polyps to be adenomatous.[41],[42],[43],[44],[45] Even with this, it has been reported that <1% of these polyps are villous or have a focus of severe dysplasia, and that they never harbor invasive carcinoma.[41],[42],[43],[45] Although in the present study the most frequent histology of the diminutive polyps was inflammatory, in contrast to the belief that these polyps never harbor invasive carcinoma, the histology of two of our patients with diminutive polyps was actually adenocarcinoma. It may therefore imply that the size of the polyp at the initial colonoscopy does not always correlate with the histology and that all polyps irrespective of the size must be biopsied or removed and sent for histology.

The most frequent histological diagnosis in our study was adenomatous polyp, which was similar to the findings from previous studies.[16],[17],[38] Of note was the high rate (5%) of adenocarcinoma among our patients. This figure was much higher than the 0.3% reported by Odom et al.[46] and the 1.1% reported by Ferlitch et al.[27] in Austria, but slightly lower than the 6% reported by Winawer et al.[47] This observation underscores the need to remove all detected polyps during colonoscopy irrespective of the size and at the same time determine the histological diagnosis. This is to ensure proper management of the patients.

Another important observation from our study was the different histological diagnosis reported for polyps from different locations in the same patients. This emphasizes the need to subject individual polyp from different locations in the colon to histological diagnosis.

  Conclusion Top

In this study,polyps were found more commonly in males and in individuals aged 50 years and above. The most common presentation was hematochezia and the most common location was the rectosigmoid colon. Most of the polyps were adenomatous. Therefore, there is a need to make colonoscopy service more widely available across the country so as to enable the screening of individuals, especially those 50 years and above. This can contribute to reduction in the incidence of CRC among Nigerians.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Weir HK, Thun MJ, Hankey BF, Ries LA, Howe HL, Wingo PA, et al. Annual report to the nation on the status of cancer, 1975-2000, featuring the uses of surveillance data for cancer prevention and control. J Natl Cancer Inst 2003;95:1276-99.  Back to cited text no. 1
Boyle P, Ferlay J. Cancer incidence and mortality in Europe, 2004. Ann Oncol 2005;16:481-8.  Back to cited text no. 2
Boyle P, Langman JS. ABC of colorectal cancer: Epidemiology. BMJ 2000;321:805-8.  Back to cited text no. 3
World Cancer Research Fund (WCRF) and American Institute for Cancer Research Food, Nutrition, Physician Activity, and the Prevention of Cancer: A Global Perspective. Washington, DC: American Institute for Cancer Research; 2007.  Back to cited text no. 4
Bond JH. Clinical evidence for the adenoma-carcinoma sequence, and the management of patients with colorectal adenomas. Semin Gastrointest Dis 2000;11:176-84.  Back to cited text no. 5
Winawer SJ. Natural history of colorectal cancer. Am J Med 1999;106:3S-6S.  Back to cited text no. 6
Lambert R, Provenzale D, Ectors N, Vainio H, Dixon MF, Atkin W, et al. Early diagnosis and prevention of sporadic colorectal cancer. Endoscopy 2001;33:1042-64.  Back to cited text no. 7
Brenner H, Haug U, Arndt V, Stegmaier C, Altenhoten L, Hoffmeister M. Low risk of colorectal cancer and advanced adenomas more than 10 yrs after negative colonoscopy. Gastroenterology 2010;138:870-6.  Back to cited text no. 8
Zauber AG, Winawer SJ, O'Brien MJ, Lansdorp-Vogelaar I, van Ballegooijen M, Hankey BF, et al. Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths. N Engl J Med 2012;366:687-96.  Back to cited text no. 9
Radaelli F, Meucci G, Minoli G; Italian Association of Hospital Gastroenterologists (AIGO). Colonoscopy practice in Italy: A prospective survey on behalf of the Italian Association of Hospital Gastroenterologists. Dig Liver Dis 2008;40:897-904.  Back to cited text no. 10
Bowles CJ, Leicester R, Romaya C, Swarbrick E, Williams CB, Epstein O. A prospective study of colonoscopy practice in the UK today: Are we adequately prepared for national colorectal cancer screening tomorrow? Gut 2004;53:277-83.  Back to cited text no. 11
Segal I. Rarity of colorectal adenomas in the African black population. Eur J Cancer Prev 1998;7:387-91.  Back to cited text no. 12
Segal I, Cooke SA, Hamilton DG, Ou Tim L. Polyps and colorectal cancer in South African Blacks. Gut 1981;22:653-7.  Back to cited text no. 13
Adesanya AA, da Rocha-Afodu JT. Colorectal cancer in Lagos: A critical review of 100 cases. Niger Postgrad Med J 2000;7:129-36.  Back to cited text no. 14
Irabor DO, Arowolo A, Afolabi AA. Colon and rectal cancer in Ibadan, Nigeria: An update. Colorectal Dis 2010;12:e43-9.  Back to cited text no. 15
Oluyemi A, Awolola N, Oyedeji O. Clinicopathologic review of polyps biopsied at colonoscopy in Lagos, Nigeria. Pan Afr Med J 2016;24:333.  Back to cited text no. 16
Alatise OI, Arigbabu AO, Agbakwuru AE, Lawal OO, Sowande OA, Odujoko OO, et al. Polyp prevalence at colonoscopy among Nigerians: A prospective observational study. Niger J Clin Pract 2014;17:756-62.  Back to cited text no. 17
[PUBMED]  [Full text]  
McCashland T, Brand R, Lyden E, de Garmo P. The time and financial impact of training fellows in endoscopy. CORI Research Project. Clinical Outcomes Research Initiative. Am J Gastroenterol 2000;95:3129-32.  Back to cited text no. 18
Qumseya BJ, Coe S, Wallace MB. The effect of polyp location and patient gender on the presence of dysplasia in colonic polyps. Clin Transl Gastroenterol 2012;3:e20.  Back to cited text no. 19
Nguyen SP, Bent S, Chen YH, Terdiman JP. Gender as a risk factor for advanced neoplasia and colorectal cancer: A systematic review and meta-analysis. Clin Gastroenterol Hepatol 2009;7:676-810.  Back to cited text no. 20
Campagnoli C, Biglia N, Altare F, Lanza MG, Lesca L, Cantamessa C, et al. Differential effects of oral conjugated estrogens and transdermal estradiol on insulin-like growth factor 1, growth hormone and sex hormone binding globulin serum levels. Gynecol Endocrinol 1993;7:251-8.  Back to cited text no. 21
Issa JP, Ottaviano YL, Celano P, Hamilton SR, Davidson NE, Baylin SB. Methylation of the oestrogen receptor CpG island links ageing and neoplasia in human colon. Nat Genet 1994;7:536-40.  Back to cited text no. 22
Foley EF, Jazaeri AA, Shupnik MA, Jazaeri O, Rice LW. Selective loss of estrogen receptor beta in malignant human colon. Cancer Res 2000;60:245-8.  Back to cited text no. 23
Everson GT, McKinley C, Kern F Jr., Mechanisms of gallstone formation in women. Effects of exogenous estrogen (Premarin) and dietary cholesterol on hepatic lipid metabolism. J Clin Invest 1991;87:237-46.  Back to cited text no. 24
Laird-Fick HS, Chahal G, Olomu A, Gardiner J, Richard J, Dimitrov N. Colonic polyp histopathology and location in a community-based sample of older adults. BMC Gastroenterol 2016;16:90.  Back to cited text no. 25
Rundle AG, Lebwohl B, Vogel R, Levine S, Neugut AI. Colonoscopic screening in average-risk individuals ages 40 to 49 vs. 50 to 59 years. Gastroenterology 2008;134:1311-5.  Back to cited text no. 26
Ferlitsch M, Reinhart K, Pramhas S, Wiener C, Gal O, Bannert C, et al. Sex-specific prevalence of adenomas, advanced adenomas, and colorectal cancer in individuals undergoing screening colonoscopy. JAMA 2011;306:1352-8.  Back to cited text no. 27
Brenner H, Hoffmeister M, Arndt V, Haug U. Gender differences in colorectal cancer: Implications for age at initiation of screening. Br J Cancer 2007;96:828-31.  Back to cited text no. 28
Itzkowitz SH. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Sleisenger MH, editors. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. Pathophysiology/Diagnosis/Management. 7th ed. Philadelphia, USA; Elsevier Saunders; 2002. p. 2175-214.  Back to cited text no. 29
Shnitka TK, Friedman MH, Kidd EG, MacKenzie WC. Villous tumours of the rectum and colon characterised by severe fluid and electrolyte loss. Surg Gynecol Obstet 1961;112:609-21.  Back to cited text no. 30
Abdulkareem FB, Abudu EK, Awolola NA, Elesha SO, Rotimi O, Akinde OR, et al. Colorectal carcinoma in Lagos and Sagamu, Southwest Nigeria: A histopathological review. World J Gastroenterol 2008;14:6531-5.  Back to cited text no. 31
Dakubo J, Kumoji R, Naaeder S, Clegg-Lamptey J. Endoscopic evaluation of the colorectum in patients presenting with haematochezia at Korle-Bu Teaching Hospital, Accra. Ghana Med J 2008;42:33-7.  Back to cited text no. 32
Ibrahim KO, Anjorin AS, Afolayan AE, Badmos KB. Morphology of colorectal carcinoma among Nigerians: A 30-year review. Niger J Clin Pract 2011;14:432-5.  Back to cited text no. 33
[PUBMED]  [Full text]  
Mehran A, Jaffe P, Efron J, Vernava A, Liberman A. Screening colonoscopy in the asymptomatic 50- to 59-year-old population. Surg Endosc 2003;17:1974-7.  Back to cited text no. 34
Nusko G, Mansmann U, Wiest G, Brueckl W, Kirchner T, Hahn EG. Right-sided shift found in metachronous colorectal adenomas. Endoscopy 2001;33:574-9.  Back to cited text no. 35
Okamoto M, Shiratori Y, Yamaji Y, Kato J, Ikenoue T, Togo G, et al. Relationship between age and site of colorectal cancer based on colonoscopy findings. Gastrointest Endosc 2002;55:548-51.  Back to cited text no. 36
Patel K, Hoffman NE. The anatomical distribution of colorectal polyps at colonoscopy. J Clin Gastroenterol 2001;33:222-5.  Back to cited text no. 37
Visovan II, Tantau M, Ciobanu L, Pascu O, Tantau A. Increasing prevalence of right-sided colonic adenomas in a high-volume endoscopy department in Romania: Implications for colorectal cancer screening. J Gastrointestin Liver Dis 2014;23:147-51.  Back to cited text no. 38
Khalid AB, Majid S, Salih M, Hashmat F, Jafri W. Is full colonoscopic examination necessary in young patients with fresh bleeding per rectum? Endoscopy 2011;43:692-6.  Back to cited text no. 39
Cheng L, Eng C, Nieman LZ, Kapadia AS, Du XL. Trends in colorectal cancer incidence by anatomic site and disease stage in the United States from 1976 to 2005. Am J Clin Oncol 2011;34:573-80.  Back to cited text no. 40
Gottlieb LS, Winawer SJ, Sternberg S, Magrath C, Diaz B, Zauber A, et al. National Polyp Study (NPS): The diminutive colonic polyp. Gastrointest Endosc 1984;30:143-  Back to cited text no. 41
Granqvist S, Gabrielsson N, Sundelin P. Diminutive colonic polyps-clinical significance and management. Endoscopy 1979;11:36-42.  Back to cited text no. 42
Weston AP, Campbell DR. Diminutive colonic polyps: Histopathology, spatial distribution, concomitant significant lesions, and treatment complications. Am J Gastroenterol 1995;90:24-8.  Back to cited text no. 43
Ryan ME, Norfleet RG, Kirchner JP, Parent K, Nunez JF, Rhodes RA, et al. Significance of diminutive colorectal polyps in 3282 flexible sigmoidoscopic examinations. Gastrointest Endosc 1985;31:149  Back to cited text no. 44
Tedesco FJ, Hendrix JC, Pickens CA, Brady PG, Mills LR. Diminutive polyps: Histopathology, spatial distribution, and clinical significance. Gastrointest Endosc 1982;28:1-5.  Back to cited text no. 45
Odom SR, Duffy SD, Barone JE, Ghevariya V, McClane SJ. The rate of adenocarcinoma in endoscopically removed colorectal polyps. Am Surg 2005;71:1024-6.  Back to cited text no. 46
Winawer SJ, Zauber AG, O'Brien MJ, Gottlieb LS, Sternberg SS, Stewart ET, et al. The National Polyp Study. Design, methods, and characteristics of patients with newly diagnosed polyps. The National Polyp Study Workgroup. Cancer 1992;70:1236-45.  Back to cited text no. 47


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1], [Table 2], [Table 3]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

  In this article
Patients and Methods
Article Figures
Article Tables

 Article Access Statistics
    PDF Downloaded120    
    Comments [Add]    

Recommend this journal