Subclass AC: Collective works
Subclass ACA: Collections
Series are serial works, often with different authors but explicitly linked together.
Subclass AE: Encyclopedias
Subclass AG: Dictionaries and general reference
Dictionaries, and general reference, can be works that list words, with meaning or other context-appropriate information, but also includes simple, sorted reference texts, such as biographical dictionaries, that follow a similar format.
Examples: Hoyt's New Cyclopedia Of Practical Quotations (Jehiel Keeler Hoyt & Kate Louise Roberts, 1922), A Dictionary of Australian Words and Terms (Gilbert H. Lawson, 1924), Easton's Bible Dictionary (Matthew George Easton, 1897).
Subclass AGA: Reference Works
Indexes are sorted lists of bibliographic information. They are usually limited to a specific form, type, format or subject.
Museums are institutions that conserve, and often display, a collection of artifacts.
Child portal: British Museum
Subclass AMA: Collectors and collecting
Collectors and collecting are people and their occupation, as either a profession or a hobby, that involves finding, acquiring and storing items of interest.
Subclass AS: Academies and learned societies
Yearbooks are annual publications in some countries that commemorate the past year of a school and its pupils.
Almanacs are annual publications that list information, data and useful facts.
Subclass AYB: Directories
Directories are sorted lists of names and information about specific types of people, business or other organisations.
Subclass AZ: History of scholarship and learning
Subclass AZA: The Humanities
The Humanities are academic disciplines that study the human condition; distinct from the empirical methods of science.