Geographical distribution of Northern pygmy owl
BirdLife International. 2016. Glaucidium californicum. The IUCN Red List of Threatened Species 2016: e.T61791401A95181072. https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T61791401A95181072.en. Downloaded on 02 June 2018.
Cephas