ScienceVariational Principles in Dynamics and Quantum Theory . Wolfgang Yourgrau and Stanley Mandelstam. Pitman, London, 1955 (U.S. distr.: Pitman, New York). viii + 155 pp. Illus. $5.50.Peter G. BergmannPublished Aug 12, 1955• 0 citationsPublisherDOI10.1126/science.122.3163.292-b