Borgström, Erik, and Lars Schütt. “A Long Term Study (1938–2004) of Arrival Dates of Migratory Birds in Middle Värmland”. Ornis Svecica 16, no. 3 (July 1, 2006): 95–111. Accessed December 12, 2025. https://journals.lub.lu.se/os/article/view/22717.