Pulliainen, E., and J. Tuomainen. “On the Nesting Biology of the Two-Barred Crossbill Loxia Leucoptera in NE Finland”. Ornis Fennica 55, no. 4 (December 31, 1978): 180–182. Accessed November 23, 2024. https://ornisfennica.journal.fi/article/view/132993.