What subjects do the call letters cover?
Subclass AC Collections. Series. Collected works.
Subclass AE Encyclopedias.
Subclass AG Dictionaries and other general reference works.
Subclass AI Indexes.
Subclass AM Museums. Collectors and collecting.
Subclass AN Newspapers.
Subclass AP Periodicals.
Subclass AS Academies and learned societies.
Subclass AY Yearbooks. Almanacs. Directories.
Subclass AZ History of scholarship and learning. The humanities.