Houghton, Bernard On-LIne information retrieval systems: An introductory manual to principles and practice - London: Clive Bingley Ltd., 1977 - 160p. ISBN: 0-208-01660-0 Subjects--Topical Terms: Library and information studies Subjects--Index Terms: Networks Boolean logic Universal Decimal Class. No.: D 002:681.3.022 / L7