Collar, N., P. F. D. Boesman, and G. M. Kirwan (2020). Cape Parrot (Poicephalus robustus), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bnnpar2.01
Collar, N. and P. F. D. Boesman (2020). Red-fronted Parrot (Poicephalus gulielmi), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.refpar5.01
Collar, N. and P. F. D. Boesman (2020). Yellow-fronted Parrot (Poicephalus flavifrons), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.yefpar4.01
Kirwan, G. M. (2020). Brown-necked Parrot (Poicephalus fuscicollis), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.brnpar1.01
Collar, N. and P. F. D. Boesman (2020). Meyer's Parrot (Poicephalus meyeri), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.meypar1.01
Collar, N. and P. F. D. Boesman (2020). Rüppell's Parrot (Poicephalus rueppellii), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.ruepar1.01
Collar, N. and P. F. D. Boesman (2020). Brown-headed Parrot (Poicephalus cryptoxanthus), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.brhpar2.01
Collar, N. and P. F. D. Boesman (2020). Niam-Niam Parrot (Poicephalus crassus), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.ninpar1.01
Collar, N. and G. M. Kirwan (2020). Senegal Parrot (Poicephalus senegalus), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.senpar.01
Collar, N., G. M. Kirwan, and P. F. D. Boesman (2020). Red-bellied Parrot (Poicephalus rufiventris), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.rebpar1.01
Gill, Frank; Donsker, David; Rasmussen, Pamela, red. (January 2023). «Hummingbirds». IOC World Bird List Version 13.1. International Ornithologists' Union. Henta 6. juli 2023.