One of the best public sources is the business section of your public, or local college or university, library. The services provided vary from library to library but usually include a wide range of government publications with market statistics, a large collection of directories with information on domestic and foreign businesses, and a wide selection of magazines, newspapers and newsletters.
This article includes a general overview of types of affiliates and agreements. Every business situation is unique, so be sure to get help from an attorney in preparing any affiliate agreement. There may be "gotcha" clauses or language that you may not have seen or included. For example, if you are the affiliate, check to see what percentage of ownership, if any, the other company has in your business.