Columbia subject headings:
Publishers and publishing--Canada--Directories.
Publishers and publishing--United States--Directories.
Harvard subject headings:
Book industries and trade--Canada--Directories.
Book industries and trade--United States--Directories
Publishers and publishing--Canada--Directories
Publishers and publishing--United States--Directories
Princeton subject headings:
Directories.
Publishers and publishing--Canada--Directories.
Publishers and publishing--United States--Directories.