List of sources:
FamilySearch: John Leslie Masson. https://ancestors.familysearch.org/en/GFQ8-KNG/john-leslie-masson-1845-1913 AND https://www.familysearch.org/ark:/61903/3:1:3Q9M-C91Q-QSRM-P?view=index&action=view&cc=2721608&lang=en
John Leslie Masson, MA. AngloBoerWar.com. Retrieved from https://www.angloboerwar.com/forum/5-medals-and-awards/10440-i-considered-it-a-piece-of-sharp-practice
on 2018-9-20.
Natal [Colony]. Civil service list, 1906, 1907.
Natal [Colony]. Report of the Surveyor-General, 1891/2-1894/5, 1896-1900, 1902-1904.
Natal almanac, directory, and yearly register, 1909, p. 55, Natal Museum: Board of Trustees.
Natal who's who, 1906.
National Automated Archival Information Retrieval System (NAAIRS). http://www.national.archives.gov.za/naairs.htm Documents relating to Masson, John Leslie / Masson, J.L. / Surveyor General Masson.
Reitz, O.G. August Hammar, 1856-1931. South African Survey Journal, 1968, Vol. 11(4), pp. 31-35; Vol. 11(5), pp. 36-45.
Royal Society of South Africa. Transactions, 1908-1910, Vol. 1: List of members.
South African Association for the Advancement of Science. Report, 1905/6, 1910: Lists of members.
South African Philosophical Society. Transactions, 1900-1907, Vol. 11, 16, 17: Lists of members.
South African who's who, 1908.