Källander, Hans. “The Recent Decline of the Swedish Black-Headed Gull Larus Ridibundus population—a Special Issue of Ornis Svecica”. Ornis Svecica 6, no. 1–2 (April 1, 1996): 1–4. Accessed April 18, 2024. https://journals.lub.lu.se/os/article/view/23130.