ROY, Frank. May Day Count, Saskatoon Natural History Society. Blue Jay, [S. l.], v. 23, n. 1, 1965. DOI: 10.29173/bluejay3165. Disponível em: https://bluejayjournal.ca/index.php/bluejay/article/view/3165. Acesso em: 3 may. 2024.