Persistent hepatitis B virus infection in subjects without hepatitis B surface antigen: Clinically significant or purely “occult”? - Bréchot, Christian; Thiers, Valérie; Kremsdorf, Dina; Nalpas, Bertrand; Pol, Stanislas; Paterlini-Bréchot, Patrizia (Hepatology (Baltimore, Md.), 2001)