Dewey Decimal Classification
Frequently-Used Standard Subdivisions
(from Table 1 of DDC 22)

—01 Philosophy and theory

—025 Directories of persons and organizations

—03 Dictionaries, encyclopedias, concordances

[—04 Special topics]

—05 Serial publications

—06 Organizations and management

—07 Education, research, related topics

—072 Research; statistical methods

—09 Historical, geographic, persons treatment

—092 Persons

—0922 Collected persons treatment

—093-099 Treatment by specific continents, countries, localities; extraterrestrial worlds