The author has more than 30 years experience in nonlinear optics, laser physics and quantum electronics. He has published more than 120 papers in peer-reviewed journals, 5 books and 7 book chapters. His first review on nonlinear optical crystals was published in 1977 (Sov.J.Quantum Electronics, vol.4, pp. 5-26) and the twenty years later selected as a MILESTONE publication (see SPIE Milestone Series, vol MS140, Selected Papers on Optical Parametric Oscillators and Amplifiers and Their Applications, ed. by J.H.Hunt, pp.191-203, 1997).