TOPRAK, Nizamettin, et al. “HEPATITIS B SURFACE ANTIGEN AND ANTIBODY LEVELS IN NORMAL POPULATION AND LN CIRRHOTIC PATIENTS”. Turkish Journal of Gastroenterology, vol. 3, no. 2, Jan. 1992, pp. 282-4, https://www.turkjgastroenterol.org/index.php/tjg/article/view/117.