Ström, Kåre, and Aimon Niklasson. “Biometry and Sex Determination in the Scarlet Rosefinch Carpodacus Erythrinus Using Size and Form of the Cloacal Protuberance”. Ornis Svecica 6, no. 3 (July 1, 1996): 97–105. Accessed April 25, 2024. https://journals.lub.lu.se/os/article/view/22985.