List of sources:
Annals of the Transvaal Museum, 1908-1910, Vol. 1-2.
Ashton, E.H. Southern African Ornithological Society. Bokmakierie, 1980, Vol. 32, pp. 26-76.
Dictionary of South African biography, Vol. 4, 1981.
FamilySearch: Alwin Karl Haagner.
Fitzsimons, V. & Brain, L. A history of the Transvaal Museum. Transvaal Museum Bulletin, 1972, No. 13, pp. 5-11.
Janse, A.J.T. A short history of the South African Biological Society. South African Biological Society Pamphlet, 1939, No. 10, pp. 49-58.
Journal of the South African Ornithologists' Union, 1905-1914, Vol. 1-10.
National Union Catalogue, pre-1956 imprints. London: Mansell, 1968-1980.
Obituary: Alwin Karl Haagner, Sc D, 1880-1962. The Ostrich, December 1962, Vol. 33(4), p. 56.
South African Association for the Advancement of Science. Report, 1905/6, 1910, 1915, 1918.
South African bibliography to the year 1925. London: Mansell, 1979.
South African Journal of Natural History, 1920, Vol. 2(2), Roll of members [of the SA Biological Society].
South African Ornithologists' Union. South African Journal of Natural History, 1918, Vol. 1, pp. 22-23.
South African who's who, 1919/20, 1927/8.
Standard encyclopedia of southern Africa (SESA). Cape Town: NASOU, 1970-1976.
Summaries of some recent botanical and zoological papers referring to South Africa. Transactions of the South African Philosophical Society, 1902, Vol. 11(4), pp. 383-418.
The Transvaal Biological Society. South African Journal of Natural History, 1918, Vol. 1, pp. 24-32.
Transvaal Museum. Annual Report, 1907/8.
Van den Berg, P., Van den Berg, I. & Hopkins, P. The first hundred years, National Zoological Gardens of South Africa. Centurion: Zoroaster, 2000.