Osma Charris, Handerson Rafael, et al. “Metastatic Anal Canal Squamous Cell Carcinoma in a Patient With HIV Treated With Concomitant Radiotherapy Chemo. Case Report and Literature Review”. Revista Colombiana De Gastroenterología, vol. 34, no. 4, Dec. 2019, pp. 438-44, doi:10.22516/25007440.290.