1. Abbott, M. B. 1966.An Introduction to the Method of Characteristics., 243New York: American Elsevier.
2. The propagation of groups of internal gravity waves in a shear flow
3. Courant, R. and Hilbert, D. 1962. “Methods of Mathematical Physics, V. 2”. 830New York: Interscience.
4. The effect of weak shear and rotation on internal waves