Mattar, Rejane, et al. “ Preoperative Serum Levels of Ca 72-4, Cea, Ca 19-9, and Alpha-Fetoprotein in Patients With Gastric Cancer ”. Revista Do Hospital Das Clínicas, vol. 57, no. 3, June 2002, pp. 89-92, https://doi.org/10.1590/S0041-87812002000300001.