Columbia subject headings:
Information storage and retrieval systems--Special collections--Directories.
Library resources--United States--Directories.
OCLC--Directories.
Harvard subject headings:
Bibliography--United States--Databases--Directories.
Libraries--Special collections
Libraries--Special collections--Databases--Directories.
Library resources
Library resources--United States--Directories
OCLC
OCLC--Directories.
Princeton subject headings:
Libraries--Special collections.
OCLC.