1. Andrewes C, Pereira HG: Viruses of Vertebrates ( 3rd edn. ). Balliere Tindall, London, 1972, p. 290–308.
2. Strauss MJ, Shaw EW, Bunting H, Melnick JL: Crystalline virus like particles from skin papillomas characterised by intranuclear inclusion bodies. Proc Soc Exp Biol Med 72: 46–50, 1949.
3. Oriel JD, Almeida JD: Demonstration of virus particles in human genital warts. Br J Vener Dis 46: 37–42, 1970.
4. Orth G, Favre M, Croissant O: Characterization of a new type of human papillomavirus that causes skin warts. J Virol 24: 108–120, 1977.
5. Gissmann L, Pfister H, zur Hausen H: Human papilloma viruses (HPV): characterization of four different isolates. Virology 76: 569–580, 1977.