1. Die Krankheiten des Mundes;Mikulicz,1898
2. The Epidemiology of Syphilis;Moore;J. A. M. A,1963
3. Extragenital Chancres; Survey of 219 Cases;Tucker;Am. J. Syph., Gonor. & Ven. Dis,1948
4. A Survey of 68 Cases of Entragenital Chancres;Wile;Am. J. Syph., Gonor. & Ven. Dis,1941
5. Incidence of Extragenital Chancres;Doroning;Arch. Dermat,1939