Core-reference collections are the small number of sources which meet the basic needs of all libraries, and the purpose of this guide is to assist libraries in the selection, acquisition, and use of these resources. Section I, structured like an annotated bibliography, focuses on the selection of those works which should constitute the main reference holdings in a small library, or a ready-reference collection in a larger library. Sources are divided into the following classifications: general works, biography, religion, language, literature, visual and performing arts, history, statistics, political science and law, geography, education and careers, business, home life and social customs, sports and recreation, and science and technology. Authority, accuracy, currency, and convenience of arrangement are the criteria used to choose reference works for inclusion, and because some are expensive, cost is also considered. Section II is designed to help small libraries in the acquisition process. Some works are recommended to be purchased on a regular basis--annually, biennially, or every 2 to 5 years. The remaining titles are arranged into five groups according to estimated reference value in descending order of importance. Section III, containing nine exercises on using basic types of resources such as almanacs, encyclopedias, and dictionaries, is intended to improve search skills and demonstrate the special value of certain reference works. (MAS)