White, A.D.; Rigden, J.D. Correspondence: Continuous gas maser operation in the visible. Proceedings of the IRE (Institute of Electrical and Electronics Engineers (IEEE)). 1962, 50 (7): 1697. ISSN 0096-8390. doi:10.1109/jrproc.1962.288157.
White, A.D.; Rigden, J.D. Correspondence: Continuous gas maser operation in the visible. Proceedings of the IRE (Institute of Electrical and Electronics Engineers (IEEE)). 1962, 50 (7): 1697. ISSN 0096-8390. doi:10.1109/jrproc.1962.288157.