1. Amadon, D., The genera of Corvidae and their relationships, Am. Mus. Novitat., 1944, no. 1251, pp. 1–21.
2. Baumel, J.J. (Ed)., Nomina Anatomica Avium. An Annotated Anatomical Dictionary of Birds, London: Academic Press, 1979.
3. Brom, T.G., Microscopic identification of feathers and feather fragments of Palearctic birds, Bijdragen tot de Dierkunde, 1986, vol. 56, pp. 181–204.
4. Brom, T.G., Villi and the phyly of Wetmore’s order Piciformes (Aves), Zool. J. Linn. Soc., 1990, vol. 98, pp. 63–72.
5. Bulyga, L.P., Sudebno-biologicheskoe issledovanie per’ev i pukha ptits (Forensic Biological Study of Bird Feathers and Down), Kiev: KNIISE, 1998.