1. T.H. Maiman, Nature 187, 493 (1960)
2. A. Kaminskii, Crystalline Lasers: physical processes and operating schemes. CRC press (Laser and Optical Sciences and Techology Series), Edition Marvin Weber (1996)
3. Fuxi Gang, Laser Materials, World Scientific Publishing Co, London (1995)
4. S.A. Payne and W.F. Krupke, A glimpse into the laser crystal ball, Optics and Photonics News (OSA) 31 (August 1996).
5. G. Boulon and R. Reisfeld, French-Israeli Workshop on Apatites and Lasers (Jerusalem-November 25–26, 1996). A special review in Optical Materials 8, no 1/2, July 1997