Geographical distribution of Dusky grouse
BirdLife International. 2016. Dendragapus obscurus. The IUCN Red List of Threatened Species 2016: e.T22734690A95095102. https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22734690A95095102.en. Downloaded on 27 June 2018.
Cephas