Integrated Taxonomic Information System (ITIS): Megascops asio (TSN 686658)itis.gov. Viitattu 8.11.2011. (englanniksi)
iucnredlist.org
BirdLife International: Megascops asioIUCN Red List of Threatened Species. Version 2022-2. 2019. International Union for Conservation of Nature, IUCN, Iucnredlist.org. Viitattu 5.1.2023. (englanniksi)