Campbell, Kimberley Ann, Stephanie Thunberg, and Christopher B Sturdy. “Features of Male- and Female-Produced Song in Black-Capped Chickadees (Poecile Atricapillus) Change Between Seasons”. Canadian Acoustics 47, no. 3 (October 16, 2019): 36-37. Accessed May 9, 2021. https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3348.