1. E. Carder (1977 ): Practical Colposcopy . Karger, Basel, p94 .
2. M. Coppleson, E. Pixley, and B. Reid (1978 ): Colposcopy , 2nd Edition . Thomas, Springfield, Illinois, p278 .
3. M. Coppleson, E. Pixley, and B. Reid (1978 ): Colposcopy , 2nd Edition . Thomas, Springfield, Illinois, p267 .
4. A. D. T. Govan, E. M. Haines, and F. A. Taylor Langley .
5. The histology and cytology of changes in the epithelium of the cervix uteri