A. Reinikainen, “The irregular migrations of the Crossbill, Loxia c. curvirostra, and their relation to the cone-crop of the Conifers”., Ornis Fenn, vol. 14, no. 2, pp. 55–64, Jul. 1937, Accessed: Dec. 23, 2025. [Online]. Available: https://ornisfennica.journal.fi/article/view/132364