Drainage basin form and process : a geomorphological approach / by K. J. Gregory and D. E. Walling. Gregory, K. J. (Kenneth John) Walling, D. E., author. Watersheds. GB561 .G73 551.4 G822d "A Halsted Press book." Includes Index. Bibliography: p. [407]-447. New York : Wiley, c1973. c1973. 1973 Text x, 456 p. : eng