Print sources:

American Horticultural Society. A-Z Encyclopedia of Garden Plants (2004).
Anderson, Miles. The World Encyclopedia of Cacti and Succulents (2000).
Bassetti, Alessandro and Stefano Sala. The Great Aloe Book (2005).
Bond, Pauline and Peter
Bornman, Hans. Aloes of the South African Veld (1971).
Court, Doreen. Succulent Flora of Southern Africa (1981).
Goldblatt, Peter and John Manning. Cape Plants: A Conspectus of the Cape Flora of South Africa (2000).
Jankowitz, W.J. Aloes of Southwest Africa (1975).
Jeppe, Barbara. South African Aloes (1974).
Klopper, R.R. et. al. Checklist of the Flowering Plants of Sub-Saharan Africa (2006).
Lebrun, J.-P. and A. Stork. Tropical African Flowering Plants (2003).
Reynolds, Gilbert Westacott. The Aloes of South Africa (1969).
Reynolds, Gilbert Westacott. The Aloes of Tropical Africa and Madagascar (1966).
Reynolds, Tom. Aloes: The Genus Aloe (2004).
Sajeva, Maurizio and Mariangela Costanzo. Succulents, The Illustrated Dictionary (1994).
Smith, Gideon. First Field Guide to Aloes of Southern Africa (2003).
Van Wyk, Ben-Erik and Gideon Smith. Guide to the Aloes of South Africa (1996).
West, O. Field Guide to the Aloes of Zimbabwe (1974).
----------. FLORA, A Gardener's Encyclopedia (2003).

Internet sources:

African Flowering Plants Database
Flora of Southern Africa Checklist
Institute for Aloe Studies
International Plant Names Index
Plants Belonging to the Genus Aloe
South African National Biodiversity Institute
Southern African Botanical Diversity Network