| abortion clinics | abrasive products | accommodation |
| accountant | accounting | accounting equipment |
| accounting general services | accounting services | acting school |
| acupuncture clinic | adjustment services | adm-communications |
| adm-communications utilities | administration of educational programs | administration of general economic programs |
| administration of manpower programs | administration of public health programs | administration of social programs |
| administration of transportation | adoption attorneys | advertising |
| advertising-computer | advertising-outdoor | advertising-promotional |
| advertising agencies | advertising counselors | advertising specialties |
| after school | after school care | after school programs |
| air cargo services | air compressor | air conditioning |
| air conditioning supplies | aircraft | aircraft dealers |
| airline companies | airline services | airport |
| alcoholic beverage | ale | alley |
| allied products | allied services | aluminum foundry |
| amusement | amusement parks | animal clinic |
| animal doctor | animal health | animal hospital |
| animal specialty services | apartment building operators | apparel manufacturer |
| appliance dealers | appliances repairing | architects |
| architectural metalwork | architectural services | armored car service |
| art gallery | artists fine arts | art school |
| athletic goods | athletic organizations | attorney |
| auditing | auto cleaning detailing | auto dealers |
| auto detailing | automation equipment | automation equipment manufacturers |
| automation system | automation systems manufacturers | automobile |
| automobile body | automobile body painting | automobile body repairing |
| automobile dealers | automobile detail | automobile detail up service |
| automobile parking | automobile parts manufacturers | automobile supplies manufacturers |
| automotive glass replacement shops | automotive repair shop | automotive transmission repair shops |
| auto polishing | auto supply stores | auto transmissions |
| auto washing polishing |
