Carlsson, Hjordis, Leif Carlsson, Christina Wallin, and Nils-Erik Wallin. “Great Tits Incubating Empty Nest Cups”. Ornis Svecica 1, no. 1 (January 1, 1991): 51–53. Accessed March 28, 2024. https://journals.lub.lu.se/os/article/view/23096.