Encyclopedia of American Industries Gale.
Two-volume summary of inofrmation on hundreds of industry groups. Please note that you can use these entries to find the NAICS number for each industry group, useful for finding data in other sources.
Associations Unlimited Gale.
Searchable database of information on over 400,000 non-governmental organizations in the U.S. and other countries, including industry and professional groups.
Select the "Subject/Any Word" to find groups concerned with a particular topic, and then use "Subject Descriptor."
Definitions of thousands of terms.
Economics and Business Dictionaries. Oxford University Press.
Searchable collection of a half-dozen dictionaries from Oxford Reference Online.