Mattos, L. C. de, Cintra, J. R., Sanches, F. E., Silva, R. de C. M. A. da, Ruiz, M. A. and Moreira, H. W. (2002) “ABO, Lewis, secretor and non-secretor phenotypes in patients infected or uninfected by the Helicobacter pylori bacillus”, São Paulo Medical Journal, 120(2), pp. 55–58. Available at: https://periodicosapm.emnuvens.com.br/spmj/article/view/2677 (Accessed: 16 October 2025).