• Advertising, Branding & Marketing Study - Industry-specific trends, statistics and market research from Plunkett Research, Ltd., a leading provider of business, Internet and industry information to the corporate, library, academic and government markets.
• Advertising Age - Has a searchable archive going back to 1995. It's free, but requires registration. The content here isn't exactly the same as the print version of the magazine: there's information on the web that's not in print and vice-versa.
• Adweek - [Fee-based]. Has a searchable archive of Brandweek, Adweek and Mediaweek going back to 1991, and MC Magazine and New Product News since 1995.
• Agency Compile - Large directory of ad agencies in the United States. Provides all kinds of info: year founded, number of employees, billings, revenues, sector. Covers both US and Canada.
• Top 25 Marketing Service Agencies - From Advertising Age, this page lists the top 25 agencies according to 1996 revenues, along with US revenues, revenues from sales promotion and direct response.

Interactive
• Interactive Advertising Agencies - Information about interactive advertising agencies, including a list of the top 50 agencies.

Lobbying
• Top Lobbying Firms - Lists the top lobbying firms, with earned income, number of clients and contributions.

Other Useful Information
• NTC's Dictionary of Advertising - [Book -- Amazon]. Over 5,000 definitions of terms and acronyms used in advertising.

Other Industry Research Links for United States
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