List of sources:
Anglo-African who's who and biographical sketch book. London: Upcott, 1910.
Dictionary of South African biography, Vol. 3, 1977.
FamilySearch: Henry Anderson Bryden. https://ancestors.familysearch.org/en/LVQL-22K/henry-anderson-bryden-1854-1937
Mendelssohn, S. South African bibliography. London, 1910.
National Union Catalogue, pre-1956 imprints. London: Mansell, 1968-1980.
Rosenthal, E. Southern African dictionary of national biography. London: F. Warne, 1966.
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.
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.
Who was who, Vol. 3, 2nd ed. London: Adam & Black, 1967.