Caption accompanying photograph: The first field experiment in history applying copper sulfate to control Planorbis snails, carrier of Bilharzia mansoni. Dr. M. Khalil applying CuSO4 in a Botanical garden stream in Georgetown the capital of British Guiana, South America in 1921.

“The National Campaign for the Treatment and Control of Bilharziasis from the Scientific and Economic Aspects.” Journal of the Royal Egyptian Medical Association 32, nos. 11 and 12 (1949): 848.