About eight years later Niels Bohr in 1913, published his famous three part series where, essentially by fiat, he posits the quantization of the angular momentum in hydrogen and hydrogen like metals. Where in effect, the orbital angular momentum L of the (valence) electron, takes the form L = l ℏ ℏ , where l is presumed a whole number 0 , 1 , 2 , 3 , … … . In the original presentation, the orbital angular momentum of the electron was named M , the Planck constant divided by two pi as M 0 , and the quantum number or "counting of number of passes between stationary points", as stated by Bohr originally as, τ τ . See references above for more detail.