Antonina Smedile, Pietro Dentico, Alessandro Zanetti, Evangelista Sagnelli, Erik Nordenfelt, Giovanni C. Actis, Mario Rizzetto,
Infection with the Delta (δ) Agent in Chronic HBsAg Carriers Gastroenterology. ,vol. 81, pp. 992- 997 ,(1981) ,
10.1016/S0016-5085(81)80003-0