1. Acocks, J. P. H. 1953. Veld Types of South Africa. Mem. Bot. Surv. S. Afr. 28:1–192.
2. Alexander, W. B. 1955. Birds of the Ocean. 2nd ed. Putnam, London.
3. Belt, T. 1874. The Naturalist in Nicaragua. Dent, London.
4. Benson, C. W., Brooke, R. K., Dowsett, R. J. & Irwin, M. P. S. 1971. The Birds of Zambia. Collins, London.
5. Benson, C. W. & Irwin, M. P. S. 1965. Some West-East distributional gaps in birds of evergreen forest in South-Central Africa. Proc. Centr. Afr. Sci. Med. Congr.: 309–320.