Attributes / relations provided by
♦ 1del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.).
Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.
♦ 2SNOW VOLE - Chionomys nivalis (Martins 1842), Janeau G., Aulagnier S., IBEX J.M.E. 4:1997