Das, P.N. An introduction to automatic telephony [for the Undergraduate students of telecommunication and electrical engineering]/ P.N. Das - 2nd ed. - Calcutta: Modern Book, 1966 - vii, 226 p.; 21 cm. Includes index Bibliography: p. 221-222 ISBN: Rs. 10.00 Subjects--Topical Terms: Telephone, DialTelephone, AutomaticTelephone relaysTelephone stationsTelephone lines Dewey Class. No.: 621.3877