Eder, J.M. (1945). "LXIII. Calculation of Exposure, Determination of Photographic Speeds, Sensitometry, and the Laws Governing Density". History of Photography. Columbia University Press: 449–457. doi:10.7312/eder91430-066. ISBN9780231883702.
Royal Photographic Society. Progress medal. Web-page listing people, who have received this medal since 1878 ("Progress Medal - the Royal Photographic Society". Archived from the original on 22 August 2012. Retrieved 19 April 2013.): "Instituted in 1878, this medal is awarded in recognition of any invention, research, publication or other contribution which has resulted in an important advance in the scientific or technological development of photography or imaging in the widest sense. This award also carries with it an Honorary Fellowship of The Society. […] 1882 Leon Warnerke […]"
Royal Photographic Society. Progress medal. Web-page listing people, who have received this medal since 1878 ("Progress Medal - the Royal Photographic Society". Archived from the original on 22 August 2012. Retrieved 19 April 2013.): "Instituted in 1878, this medal is awarded in recognition of any invention, research, publication or other contribution which has resulted in an important advance in the scientific or technological development of photography or imaging in the widest sense. This award also carries with it an Honorary Fellowship of The Society. […] 1882 Leon Warnerke […]"