Ponomartsev, Sergey, Petr Valasek, Ketan Patel, and Yegor Malashichev. “Neural Crest Contribution to the Avian Shoulder Girdle and Implications to Girdle Evolution in Vertebrates”. Biological Communications 62, no. 1 (April 1, 2017): 26–37. Accessed October 30, 2020. https://biocomm.spbu.ru/article/view/6.