1. See e.g. C. Larmat et al., Phys. Today 63, 31 (2010) and references therein
2. M. Fink, IEEE Trans. Ultrason. Ferroelec. Freq. Contr. 39, 555 (1992)
3. e.g., M. Ducloy, Festkörperprobleme-Advances in Solid-State Physics (Vieweg, Braunschweig, 1982), Vol. 22, p. 35
4. Optical Phase Conjugation, edited by M. Gower, D. Proch (Springer Verlag, Berlin, 1994)
5. V.G. Veselago, Sov. Phys. Usp. 10, 509 (1968)