Differential equations : their solution using symmetries / Hans Stephani ; edited by Malcolm MacCallum. Stephani, Hans. MacCallum, M. A. H. Differential equations Numerical solutions. Symmetry. QA371 .S8473 1989 515.35 19 STD Includes bibliographical references (p. [253]-254). Cambridge [England] ; New York : Cambridge University Press, 1989. 1989. 1989 Text xii, 260 p. : http://www.loc.gov/catdir/description/cam023/88036744.html http://www.loc.gov/catdir/toc/cam021/88036744.html eng