Bohr-Sommerfeld model (1916)

Refinement of the Bohr model that starts to take quantum angular momentum into account in order to explain missing lines that would have been othrwise observed TODO specific example of such line.

They are not observe because they would violate the conservation of angular momentum.

Introduces the azimuthal quantum number and magnetic quantum number.

TODO confirm year and paper, Wikipedia points to: zenodo.org/record/1424309#.yotqe3xmjhe