This reference list was compiled to offer Maine librarians who serve communities with the resources of small- or medium-sized libraries a starting point to assess their reference collections for breadth and depth. Initially based on a list distributed by the Vermont Department of Libraries in 1987, this guide evaluates reference materials on the basis of their timeliness, effectiveness in responding to frequently asked questions, and reasonable cost. It is recommended that reference works be chosen using the same standards as for other nonfiction--i.e., currency, accuracy, authoritativeness, and ease of use. Librarians are also advised to analyze the particular needs of their community's information users before selecting books from this list. Each entry includes the book's title and author, other bibliographic information, availability (where appropriate), and cost. Three basic tools that can answer many common reference questions are highlighted: a multi-volume encyclopedia, a current world almanac, and an all-purpose dictionary. Seventeen other basic reference works are also described, including maps, telephone directories, and books of quotations. Sixteen reference works to supplement the basic 20 sources--e.g., literature guides, travel guides, and law dictionaries--are discussed. A checklist with titles of 17 Maine and local community resources concludes the guide. (SD)