Yourgrau, Wolfgang Variational principles in dynamics and quantum theory/ Wolfgang Yourgrau, Stanley Mandelstam. - New York: Dover, 1979, c1968. - xiii, 201 p.: graphs; 21 cm. Includes bibliographies and index. ISBN: 0486637735 : LCCN: 78073521 Subjects--Topical Terms: Variational principles.Dynamics.Quantum theory. Dewey Class. No.: 530.15 / Y81v