Bohr, N. "The Quantum Postulate and the Recent Development of Atomic Theory." Nature Supplement, vol. 121, 14 Apr 1928, pp. 580–90.
de Broglie, L. Comptes rendus de l'Académie des Sciences, vol. 177, 1923, pp. 507–10. English translation, www.davis-inc.com/physics/rendus-e.pdf.
Schrödinger, E. "An Undulatory Theory of the Mechanics of Atoms and Molecules," Physical Review, vol 28., no. 6, 1926, pp. 1049–70, doi:10.1103/PhysRev.28.1049.