The audiovisual (AV) field has been expanding rapidly, although in the last year or so there is evidence of a healthy slowing down in growth. This fourth edition of the guide to the AV industry represents an attempt to keep abreast of the information and to provide a single publication listing the many types of AV organizations and products which are relevant to education. Listed by section are producers and distributers of AV material; the manufacturers of equipment; associations; educational radio and television stations; reference works, serial and review publications; and a 1972-73 calendar of AV exhibits and conferences. In addition, classified indexes are provided to help the user locate firms producing specific media or manufacturing particular equipment. Entries under producers or manufacturers are alphabetically arranged by company name, and information includes key personnel, addresses, phone numbers, grade level and subject areas of materials offered, trade and professional affiliations, and the availability of catalogs and brochures. Two additional indexes are offered: an alphabetical listing of all entries with page references, and a subject index indicating firms producing AV materials in 19 subject areas. (Author/SH)