1. A. Y. Wong, R. W. Motley and N. D’Angelo, Princeton University Plasma Physics Laboratory Report MATT-177 (1963);
2. Propagation and Damping of Ion Acoustic Waves in Highly Ionized Plasmas
3. R. W. Motley and A. Y. Wong, Princeton University Plasma Physics Laboratory Internal Memo Q-3 (1963). The authors are extremely grateful to Dr. Motley and Dr. Wong for having made available the results of their investigations.