Källander, Hans. “Learning the Task: Age-Related Differences in the Proficiency of Black-Headed Gulls Kleptoparasitising Lapwings”. Ornis Svecica 10, no. 1 (January 1, 2000): 7–12. Accessed April 24, 2024. https://journals.lub.lu.se/os/article/view/22883.