Khalef, Adian Thamer. “Early In Pregnancy, Serum Activin-A Levels Can Be Used To Differentiate Between An Ectopic Pregnancy And A Normal Intrauterine Pregnancy”. Adolescência e Saúde 21, no. 6s (August 17, 2026): 634–639. Accessed August 23, 2026. https://adolescenciaesaude.com/index.php/aes/article/view/1666.