Hunowi, I. 2006. Ghost birds of Sulawesi: surveys and conservation of nightjars and owls. BirdingASIA 6: 7-8.
Sykes, B. 2009. OBC conservation: news update and requests for practical help. BirdingASIA 12: 107-108.
BirdLife International (2020) Species factsheet: Otus siaoensis. Downloaded from http://www.birdlife.org on 22/10/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/10/2020.