1. Amaral MJL, Fernandes AP, Bào SN, Recco-Pimental SM (1999) Ultrastructural study of the spermiogenesis in three species of Physalaemus (Anura, Leptodactylidae). Biocell 23:211–221
2. Baccetti B, Bigliardi E, Burini AG (1980) The morphogenesis of vertebrate perforatorium. J Ultrastruct Res 71:272–287. doi: 10.1016/S0022-5320(80)90079-9
3. Baker CL (1962) Spermatozoa of Amphiumae: spermateleosis, helical motility and reversibility. J Tenn Acad Sci 37:23–39
4. Baker CL (1965) The male urogenital system of the Salamandridae. J Tenn Acad Sci 40:1–5
5. Baker CL (1966) Spermatozoa and spermateleosis in the Salamandridae with electron microscopy of Diemictylus. J Tenn Acad Sci 41:2–25