Bull. Bur. Stand. 8, p. 543. Contains a very simple and clear proof of the displacement law.
P. Ehrenfest, Strahlungshypothesen, Ann. d. Phys. 36, p. 91.
A. Joffé, Theorie der Strahlung, Ann. d. Phys. 36, p. 534.
Discussions of the method of derivation of the radiation formula are given in many papers on the subject. In addition to those quoted elsewhere may be mentioned:
C. Benedicks, Ueber die Herleitung von Planck's Energieverteilungsgesetz Ann. d. Phys. 42, p. 133. Derives Planck's law without the help of the quantum theory. The law of equipartition of energy is avoided by the assumption that solids are not always monatomic, but that, with decreasing temperature, the atoms form atomic complexes, thus changing the number of degrees of freedom. The equipartition principle applies only to the free atoms.
P. Debye, Planck's Strahlungsformel, Ann. d. Phys. 33, p. 1427. This method is fully discussed by Wien (see 4, above). It somewhat resembles Jeans' method ([sect:169.] Sec. 169) since it avoids all reference to resonators of any particular kind and merely establishes the most probable energy distribution. It differs, however, from Jeans' method by the assumption of discrete energy quanta . The physical nature of these units is not discussed at all and it is also left undecided whether it is a property of matter or of the ether or perhaps a