RNA Structure and Function . Edited by Robert W. Simons and Marianne Grunberg-Manago. Cold Spring Harbor Laboratory Press 1997. 741 pages. Price $145. ISBN 0 87969 509 9. Retroviruses . Edited by John M. Coffin, Stephen H. Hughes and Harold E. Varmus. Cold Spring Harbor Laboratory Press 1997. 843 pages. Price $180. ISBN 0 87969 497 1.