Guide to Reference, published in 2008 as the online successor to "Guide to Reference Books", was a selective guide to the best print and online reference sources. An editorial team of reference librarians and subject experts selected and annotated some 16,000 entries, which were organized by subject. It was a subscription database, published by the American Library Association, and was updated on an ongoing basis. It was intended as a resource for libraries when answering reference questions, planning library instruction, identifying items to purchase, and training staff.