Bulatov, V.V. and Vladimirov, Y.V.  
Internal gravity waves in 
heterogeneous media.  
Nauka Publishing Company, 2005, 
195 pages (in Russian)  

The summary

The monograph is dedicated to the research of the excitation and development processes of internal gravity waves in vertically stratified, horizontally heterogeneous and time-varying media; to development asymptotic methods which generalize space-time ray-trace methods (i.e. geometrical optics method ); to the research of critical phenomena with internal gravity waves generation and propagation; to the development of non-spectral analysis methods for natural measure of internal waves in the ocean.