Bensch, Staffan, Lars G R Nilsson, Per Nothagen, Peter Olsson, and Mikael Åkesson. “A Chiffchaff Phylloscopus C. Collybita With Mixed Chiffchaff and Willow Warbler Ph. Trochilus song—genetic Evidence”. Ornis Svecica 11, no. 1–2 (April 1, 2001): 108–111. Accessed April 26, 2024. https://journals.lub.lu.se/os/article/view/22869.