When doing Industry research you will need to research the companies that are part of the industry.
Not only does that mean you will know the players, but in some cases the information that the companies say about themselves and what they say about the industry as a whole when used with that same information from other companies and what is found doing other research, will be a way to develop your own "market research" report if you can't afford to buy one from a large vendor.
Securities and Exchange Commission filings can be used to do more than tell you about a specific company. They can be used to find out details about industries, and not just those that are dominated by large public companies.
The 10K filing is the annual filing that every company files. Each has several sections but, it is Item 1 where a company tells you about itself and often about their competition. How this is handled by each company differs, but often how they report is how they are organized. For example, a researcher is interested in the oil and gas industry but is really only interested in looking at the downstream sector. Since the 10K filings of a company frequently present their information how they are organized, they can see activities presented as Upstream and Downstream. Not only did this researcher, who is more interested in the downstream industry, find out about a company and the larger industry, but they also gained some insight into only a company's downstream activities. Add this to their other research and fhey can then do the same with other companies and develop a more complete picture.
This type of research can also be helpful for those industries that may not stand on their own or if they are really just a specialized subset of something larger. First, you would need to find the company or companies that do this specific thing. If any of the companies are public, look at the 10Ks for each of them, specifically Item 1, and see if they are reporting on that particular sector and their competition.
The "Doing Company Research Guide," also prepared by Business Reference staff, includes a lot more information, sources, and strategies for company research.