Bell System Technical Journal, Vol. 51 (No. 2, Feb. 1972), pp. 371-390.
Copyright 1972 by Americam Telephone and Telegraph Company
Pages 371, 372, 373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384, 385, 386, 387, 388, 389, 390
