Geographical distribution of Long-tailed duck.   Breeding  Migration  Nonbreeding
BirdLife International. 2017. Clangula hyemalis (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22680427A112395330. https://dx.doi.org/10.2305/IUCN.UK.2017-1.RLTS.T22680427A112395330.en. Downloaded on 29 June 2018.
Cephas