1. Gaugain-Helmholtz (?) Coils for Uniform Magnetic Fields
2. J. C. Maxwell, A Treatise on Electricity and Magnetism (Dover, New York, 1954), Vol. II, p. 356.
3. O. D. Jefimenko, Electricity and Magnetism: An Introduction to the Theory of Electric and Magnetic Fields (Merideth, New York, 1966), pp. 379–380.