* {{cite book | last=Owls | first=World Working Group on Birds of Prey and | title=Raptors at Risk | publisher=Surrey, B.C. : Hancock House Publishers | publication-place=Berlin Surrey | date=2000 | isbn=0-88839-478-0}}
<ref name="h735">{{cite book | last=Owls | first=World Working Group on Birds of Prey and | title=Raptors at Risk | publisher=Surrey, B.C. : Hancock House Publishers | publication-place=Berlin Surrey | date=2000 | isbn=0-88839-478-0 | page=}}</ref>