1. Harrap, S., and D. Quinn (1996). Tits, Nuthatches and Treecreepers. Christopher Helm, London, UK.
2. Red’kin, Y. and Konovalova, M. (2006). Systematic notes on Asian birds. 63. The eastern Asiatic races of Sitta europaea Linnaeus, 1758. Zool. Meded. Leiden 80(5): 241-261.
3. Zink, R.M., Drovetski, S.V. and Rohwer, S. (2006). Selective neutrality of mitochondrial ND2 sequences, phylogeography and species limits in Sitta europaea. Mol. Phylogen. Evol. 40: 679-686.
4. Leonovich, V.V., Demina, G.V. and Veprintseva, O.D. (1996). [Sitta europaea L. and “small” nuthatches S. villosa Verreaux and S. krueperi Pelzeln: problems of taxonomy and phylogeny]. Byull. Mosk. Ova. Ispyt. Prir. Otd. Biol. 101(1): 37–49. In Russian with English summary.
5. Humphrey, P. S., and K. C. Parkes (1959). An approach to the study of molts and plumages. Auk 76(1):1–31.