Thomson, William (1884). "Electrical Units of Measurement". The Practical Applications of Electricity. Institution of Civil Engineers. pp. 149–174 at p 171 (Lecture given 3 May 1883). Available online. Thomson helpfully added that the proper pronunciation of "mho" could be obtained by taking a phonograph and turning it backwards.
bipm.org
Minutes(PDF). 14th General Conference on Weights and Measures. 1971. p. 53.
Minutes(PDF). 14th General Conference on Weights and Measures. 1971. p. 78.