van Zyl, Anthony (November 2006). Raptors of the world: a field guide by James Ferguson-Lees and David Christie. Ostrich. 77 (3–4): 235—236. doi:10.2989/00306520609485540. ISSN0030-6525.
HOLT, P. (February 1994). MUNDY, P., BUTCHART, D., LEDGER, J. and PIPER, S.The vultures of Africa. Academic Press, London: 1992 (originally published by Acorn Books, Johannesburg: 1992). Pp 460; illustrated. Price: £55.00. Archives of Natural History. 21 (1): 136. doi:10.3366/anh.1994.21.1.136. ISBN978-0-12-510585-9. ISSN0260-9541.
Gidlow, R.M. (September 2002). The history of exchange controls in South Africa. South African Journal of Economic History. 17 (1–2): 25—48. doi:10.1080/10113430209511143. ISSN1011-3436.
Mikula, P.; Morelli, F.; Lučan, R. K.; Jones, D. N.; Tryjanowski, P. (2016). Bats as prey of diurnal birds: a global perspective. Mammal Review. 46 (3): 160—174. doi:10.1111/mam.12060.
Carneiro, C.; Henriques, M.; Barbosa, C.; Tchantchalam, Q.; Regalla, A.; Patrício, A.R.; Catry, P. (2017). Ecology and behaviour of palm-nut vultures Gypohierax angolensis in the Bijagós Archipelago, Guinea-Bissau. Ostrich. 88 (2): 113—121. doi:10.2989/00306525.2017.1291540.
van Zyl, Anthony (November 2006). Raptors of the world: a field guide by James Ferguson-Lees and David Christie. Ostrich. 77 (3–4): 235—236. doi:10.2989/00306520609485540. ISSN0030-6525.
HOLT, P. (February 1994). MUNDY, P., BUTCHART, D., LEDGER, J. and PIPER, S.The vultures of Africa. Academic Press, London: 1992 (originally published by Acorn Books, Johannesburg: 1992). Pp 460; illustrated. Price: £55.00. Archives of Natural History. 21 (1): 136. doi:10.3366/anh.1994.21.1.136. ISBN978-0-12-510585-9. ISSN0260-9541.
Gidlow, R.M. (September 2002). The history of exchange controls in South Africa. South African Journal of Economic History. 17 (1–2): 25—48. doi:10.1080/10113430209511143. ISSN1011-3436.