ISBN 3-8311-3626-2[http://books.google.com/books?id=pgQKHGqYXtgC&dq=]* Döttlinger, H. & M. Nicholls (2005): Distribution and population trends of the 'black shaheen' Peregrine Falcon "Falco peregrinus peregrinator" and the eastern Peregrine Falcon "F. p. calidus" in Sri Lanka.
ISBN 3-8311-3626-2* Döttlinger, H. & M. Nicholls (2005): Distribution and population trends of the 'black shaheen' Peregrine Falcon "Falco peregrinus peregrinator" and the eastern Peregrine Falcon "F. p. calidus" in Sri Lanka.