Frank B.Gill, Beth Slikas ja Frederick H. Sheldon: Phylogeny of titmice (Paridae): II. Species relationships based on sequences of the mitochondrial cytochrome-b gene. Auk, 2005, 122. vsk, nro 1, s. 121–143. doi:10.1642/0004-8038(2005)122[0121:POTPIS]2.0.CO;2(englanniksi)
BirdLife International: Cyanistes caeruleusIUCN Red List of Threatened Species. Version 2022-2. 2017. International Union for Conservation of Nature, IUCN, Iucnredlist.org. Viitattu 25.1.2023. (englanniksi)