Anfuso, S., E. Soncini, and P. Bonelli, et al. 2007. “Second-Trimester Maternal Serum Alpha-Fetoprotein Elevation and Its Association With Adverse Maternal Fetal Outcome: Ten Years Experience”. Acta Biomedica Atenei Parmensis 78 (3): 214-19. https://mattioli1885journals.com/index.php/actabiomedica/article/view/1905.