1. C. S. Liu, inAdvances in Plasma Physics, edited by A. Simon and W. B. Thomspon (Wiley, New York, 1976), Vol. 6, Part I.
2. Absolute Parametric Instabilities in Inhomogeneous Plasmas
3. T. W. Johnston, G. Picard, J. P. Matte, V. Fuchs, and M. Shoucri, submitted to Plasma Phys. Controlled Nucl. Fusion; G. Picard, th̀se Ph.D., INRS-Energie, Université du Québec, 1983.
4. J. Heading,An Introduction to Phase Integral Methods(Wiley, New York, 1962).
5. An interactive code for solving differential equations, using phase integral methods