1. T. Maiman: Stimulated optical radiation in ruby masers, Nature 187, 493–494 (1960)
2. A. Javan, W. R. Bennett, D. R. Herriott: Population inversion and continuous optical maser oscillation in a gas discharge containing a He-Ne mixture, Phys. Rev. Lett. 6, 106–110 (1961)
3. D. H. Sliney: The development of laser safety criteria biological considerations. In: Laser applications in medicine and biology, Vol. 1, ed. by M. L. Wolbarsht (Plenum, New York 1971) pp. 163–238
4. World Health Organization (WHO): Lasers and Optical Radiation, Environmental Health criteria, no. 23 (WHO, Geneva 1982)
5. H.-D. Reidenbach: Hochfrequenz- und Lasertechnik in der Medizin (Springer, Berlin, Heidelberg 1983)