List of sources:
August von Pelzeln. In Wikipedia. http://en.wikipedia.org
Fock, G.J. Emil Holub (1847-1902), ein Afrikaforscher aus Boehmen. Journal of the South West Africa Scientific Society, 1976/7, Vol. 31, pp. 99-109.
National Union Catalogue, pre-1956 imprints. London: Mansell, 1968-1980.
Royal Society of London. Catalogue of scientific papers [1800-1900]. London: Royal Society, 1867-1925.
South African bibliography to the year 1925. London: Mansell, 1979.
Spohr, O.H. Emil Holub and August von Pelzein look at the birdlife of South Africa in the 1870's. Bokmakierie, 1979, Vol. 31, pp. 37-39.