Book Reviews —M. D. Mesarovic, D. Macko, and Y. Takahara, Theory of Hierarchical Multilevel Systems, Academic Press, New York, N. Y., 1970, 294 pages, $15.00—reviewed by Rudolf Drenick; —Donald A. Pierre, Optimisation Theory with Applications, John Wiley & Sons, New York, N. Y., 1969, 628 pages, $16.95—reviewed by David D. Morrison.