He became one of the founders of quantum mechanics; some of his contributions included co-discovery of the Sommerfeld Wilson quantization rules ( 1915 ), a Bohr's atomic model, introduction of the Sommerfeld fine-structure constant ( 1916 ), co-discovery with Walther Kossel of the Sommerfeld Kossel displacement law ( 1919 ), and publishing " Atombau und Spektrallinien " ( 1919 ), which became the " bible " of atomic theory for the new generation of physicists who developed atomic and quantum physics.
