Tham khảo Hù_nivicon

  1. ↑ BirdLife International (2016). “Strix aluco”. IUCN Red List of Threatened Species. 2016: e.T22725469A86871093. doi:10.2305/IUCN.UK.2016-3.RLTS.T22725469A86871093.en.
  2. ↑ CRC Handbook of Avian Body Masses by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0849342585.
  3. ↑ (2011).