Luis Boya, University of Zaragoza, Spain
Arnold Sommerfeld and Niels Bohr: comparison of the schools at Munich and Copenhagen at the time of the Old Quantum Theory

A comparative study is presented of the two main centres in which the Old Quantum Theory, 1913 ‒ 1925, was developed: the Munich school with A. Sommerfeld and the Copenhagen school with N. Bohr. The later was mainly based in the correspondence principle, the second on application of strict mathematical quantization rules; the comparison covers several items, including selection rules for forbidden lines.