BioStor
 | June 20, 1871 R Hadson (1871) Proceedings of The Zoological Society of London 1871: 543-622 |
 | Zoological Researches in Liberia (1888) Notes From The Leyden Museum 10: 59-106 |
 | Another small Contribution to African Ornithology (1900) Novitates Zoologicae 7: 25-53 |