CHICKADEE AT NEST-HOLE, WITH FOOD FOR YOUNG, From <a href="//commons.wikimedia.org/w/index.php?title=Bird_Lore_(1899)/The_Camera_as_an_Aid_in_the_Study_of_Birds&amp;action=edit&amp;redlink=1" class="new" title="Bird Lore (1899)/The Camera as an Aid in the Study of Birds (page does not exist)">The Camera as an Aid in the Study of Birds</a> in <i><a href="https://en.wikisource.org/wiki/en:Bird-Lore/Volume_01/No._1" class="extiw" title="s:en:Bird-Lore/Volume 01/No. 1">Bird-Lore, Vol. I, No. 1</a>.</i>
Dr. Thos. S. Roberts
<a rel="nofollow" class="external text" href="https://archive.org/details/birdlore12nati">The Internet Archive</a>