A RETRIEVAL MODEL WAS DEVELOPED FOR TEACHING AND RESEARCH PURPOSES ON THE BASIS OF VARIED WORK EXPERIENCE AND ANALYSIS OF TECHNICAL DOCUMENT RETRIEVAL AND LIBRARY SERVICES. THE MODEL IS BASED ON SHANNON'S COMMUNICATION MODEL BUT IDENTIFIES THE WOULD BE READER, OR DESTINATION OF RECORDED MESSAGES, AS THE ACTIVATOR OF RETRIEVAL SERVICES. TWO MAIN RETRIEVAL FUNCTIONS ARE SPECIFIED-- IDENTIFYING APPROPRIATE DOCUMENTS UPON REQUEST, AND DELIVERING COPIES OF IDENTIFIED DOCUMENTS. DOCUMENT REQUESTS ARE ANALYZED INTO TWO PARTS, A DESCRIPTION OF DOCUMENT AND A SPECIFICATION OF TYPE OF PHYSICAL ACCESS PREFERRED TO THE REQUESTED DOCUMENT. TO CARRY OUT RETRIEVAL WORK, FOUR KINDS OF RECORDS AND FIVE BASIC OPERATIONS ARE DEFINED. RETRIEVAL PROCESSES, SUCH AS ACQUISITION, INDEXING, AND CIRCULATION, ARE SHOWN TO CONSIST OF VARIOUS COMBINATIONS OF TWO OR MORE OF THE OPERATIONS BEING PERFORMED ON ONE OR MORE KINDS OF RETRIEVAL RECORDS. DATA RETRIEVAL IS SHOWN TO BE A SPECIAL KIND OF DOCUMENT RETRIEVAL. A HISTORY OF EQUIPMENT OF RETRIEVAL INTEREST IS PRESENTED IN A TABULAR FORMAT WITH CITATIONS OF THE APPLICATION OF EACH TYPE OF EQUIPMENT TO RETRIEVAL WORK. THIS DOCUMENT IS AVAILABLE AS AD-664-596 FROM THE CLEARINGHOUSE FOR FEDERAL SCIENTIFIC AND TECHNICAL INFORMATION, SPRINGFIELD, VIRGINIA 22151, $3.00 FOR HARD COPY, $0.65 FOR MICROFICHE, 230 PAGES. (AUTHOR)