Mattos, Luiz Carlos de, Juliana Rodrigues Cintra, Fábio Eduardo Sanches, Rita de Cássia Martins Alves da Silva, Milton Artur Ruiz, and Haroldo Wilson Moreira. 2002. “ABO, Lewis, Secretor and Non-Secretor Phenotypes in Patients Infected or Uninfected by the Helicobacter Pylori Bacillus”. São Paulo Medical Journal 120 (2):55-58. https://periodicosapm.emnuvens.com.br/spmj/article/view/2677.