Dale, Svein. “Ecology of a Two-Barred Crossbill (Loxia Leucoptera) Irruption to Norway in 2019–20: Altitudinal Migration and Interspecific Habitat Differences”. Ornis Norvegica 44 (September 7, 2021): 19–30. Accessed April 25, 2024. https://boap.uib.no/index.php/ornis/article/view/3265.