↑ Gould, R. Gordon (1959). "The LASER, Light Amplification by Stimulated Emission of Radiation". in Franken, P.A. and Sands, R.H. (Eds.). The Ann Arbor Conference on Optical Pumping, the University of Michigan, 15 June through 18 June 1959. pp. 128. OCLC 02460155.
