Selective: Assigned to a subject area in which few selections are made beyond a few basic works.
Basic: Judicious selections are made which serve to introduce and define the subject and to indicate the varieties of information available elsewhere. Included are editions of particularly important works in the subject, dictionaries and encyclopedias, handbooks, manuals, bibliographies and, where applicable, historical surveys.
Advanced Basic: An attempt is made to collect at a level sufficient to support knowledge of the subject for limited or generalized purposes, at less than research intensity. Included are currently published monographs, a limited number of important retrospective monographs, a broad selection of works on important sub-topics, and a broad selection of works from standard publishers and primary authors in the field. Works representing the broad range of “schools of thought”, methodologies or, as applicable, ideologies within the subject are sought.
Research: The characteristics of the Advanced Basic level are met. In addition, specialized monographs, a wide range of primary resources, retrospective monographs where applicable, and works of secondary as well as primary authors and publishers are sought. Contents of works may include research reports, new findings, unorthodox views or esoteric sources. An attempt is made to establish a collection sufficient to enable in-depth research in the subject area or sustained independent study.