Acharya, M.N. et al. 2013. Poorly-Differentiated Signet-Ring Cell Carcinoma of the Ampulla of Vater: Report of a Rare Malignancy. JOP. Journal of the Pancreas. 14, 2 (Mar. 2013), 190–194. DOI:https://doi.org/10.6092/1590-8577/1267.