Integrated Taxonomic Information System (ITIS): Otus insularis (TSN 202272)itis.gov. Viitattu 6.1.2012. (englanniksi)
iucnredlist.org
BirdLife International: Otus insularisIUCN Red List of Threatened Species. Version 2021-3. 2021. International Union for Conservation of Nature, IUCN, Iucnredlist.org. Viitattu 9.12.2021. (englanniksi)