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hbw.com
(en) Kemp, A.C. & Christie, D.A., 2019. Madagascar Serpent-eagle (Eutriorchis astur). In: del Hoyo, J et al (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53020 on 21 June 2019).