The polarization of radiation scattered by an electronic system in a magnetic field is worked out on the classical theory. It is shown that it is improbable that the experimental facts can be accounted for on a classical analogy. Instead, a quantum hypothesis is made which appears to account for the phenomena more satisfactorily.
G. BREIT, "POLARIZATION OF RADIATION SCATTERED BY AN ELECTRONIC SYSTEM IN A MAGNETIC FIELD," J. Opt. Soc. Am. 12, 195-205 (1926)