Ibid. P. 170 ff.

Ibid. P. 224 ff.

Gladwin, East is a Big Bird. P. 196 ff.

Swan, L. W., Tales of the Himalaya: Adventures of a Naturalist (Mountain N’ Air Books, 2000).

Hawkes, L. A., Batbayar, N., Butler, P. J., Chua, B., Frappell, P. B., Meir, J. U., … & Takekawa, J. Y. (2017). ‘Do bar-headed geese train for high altitude flights?’, Integrative and Comparative Biology, 57 (2). P. 240–251.