Jardine, W. (1836). "The Elephant of Africa". The Naturalist's Library. Vol. Volume V. Natural History of the Pachydermes, Or, Thick-skinned Quadrupeds. Edinburgh, London, Dublin: W.H. Lizars, Samuel Highley, W. Curry, jun. & Company. pp. 124–132. {{cite book}}: |volume= has extra text (help)
Laws, R. M. (1966). "Age criteria for the African elephant: Loxodonta a. africana". African Journal of Ecology. 4 (1): 1–37. doi:10.1111/j.1365-2028.1966.tb00878.x.
Laws, R. M. (1966). "Age criteria for the African elephant: Loxodonta a. africana". African Journal of Ecology. 4 (1): 1–37. doi:10.1111/j.1365-2028.1966.tb00878.x.