1. The method of saddle point in the diffraction problem;Yarygin;Radioteknika i Elektronia,1970
2. Heuristic criteria of geometrical optics applicability and adjacent questions;Kravtsov,1979
3. English translation, Springer, Berlin, to appear.
4. Geometrical Optics of Inhomogeneous Media;Kravtsov,1980
5. Limits of applicability of the method of geometric optics and related problems;Kravtsov;Sov. Phys. Usp.,1980