Trade Publications are a great source for industry information, as they are published by and for people in a particular industry.
Industry and trade associations are very similar to trade publications, as they contain information from groups and individuals who are part of the industry.
The popular press, including newspapers and magazines, often offers very recent coverage of an industry. While not as comprehensive as trade publications, news articles can be a good way to find information on your topic, particularly for those smaller niche industries. For Business and Industry news, try Factiva or Nexis Uni.