
Letter to Robert W. Wood (October 7, 1931) in Archive for the History of Quantum Physics, Microfilm 66, 5, as cited in Thomas S. Kuhn, Black-Body Theory and the Quantum Discontinuity, 1894–1912 (1978) pp. 132, 288. Translation of the entire letter, which is follow above is in Armin Hermann, Frühgeschiche der Quantentheorie (1899–1913) Mosbach/Baden: Physik Verlag (1969), transl. Claude W. Nash, p. 23 of the translation; and also in M. S. Longair,Theoretical Concepts in Physics(Cambridge and NewYork: Cambridge University Press, 1984), ch. 6–12, p. 222. All as quoted/cited by Clayton A. Gearhart, "Planck, the Quantum, and the Historians" http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.613.4262&rep=rep1&type=pdf, Physics in Perspective, 4 (2002) 170-215.