R. Mattar, C. R. A. de Andrade, G. M. DiFavero, J. J. Gama-Rodrigues, and A. A. Laudanna, “ Preoperative serum levels of ca 72-4, cea, ca 19-9, and Alpha-fetoprotein in patients with gastric cancer ”, Rev. Hosp. Clín., vol. 57, no. 3, pp. 89–92, Jun. 2002, doi: 10.1590/S0041-87812002000300001.