Click on the Data Axle "Advanced" tab to filter companies by geography and line of business.
Check to box beside Keyword/SIC/NAICS and select the radio button beside "Search Primary NAICS Only". In the search box for NAICS codes enter a term (start with "employment"). Lines of business for companies that have primary and secondary NAICS codes related to employment can be found by clicking on the code description. Next click on the City/State check box and select Maine. Click on the link for "Update Count" and then view results.
Some NAICS to get you started with your research:
After you log in to D&B Hoovers click on the tile that says, " Build a Company List". In the State/Province box enter "Maine, United States". In the Industries area enter "Employment Services" in the D&B Hoovers Industries box, and click the Primary and Secondary radio button. Click "View Results" for a list of companies in Maine offering employment services.