Kelley Walter G The theory of differential equations : classical and qualitative / Walter Kelley, Allan Peterson. - Upper Saddle River, N.J. : Prentice Education, 2004. - xi, 413 p. : ill. ; 24 cm. Includes bibliographical references (p. 405-407) and index. ISBN: 0131020269 Subjects--Topical Terms: Differential equations LC Class. No.: QA431 Dewey Class. No.: 515/.35