A source, (A.K.A. a resource, publication, article within a publication, blog, textbook, etc.) provides you with information about something. Ideally, this will be relevant (meets your information need) and credible (trustworthy) information.
As a marketing industry professional in an academic setting, you may find yourself with a dilemma. In your critical writing and other courses, you learned that one of the most credible sources to use were scholarly or peer-reviewed journals. This is true - these sources are extremely credible and verifiable. However, as a practicing professional they are not always relevant to your immediate need. As someone analyzing a marketing campaign or looking for new practices and methods, you will find yourself relying on publications written not just by academics and professors, but by individuals and journalists with experience in advertising, creating, marketing, etc.
As a result of this, you need to expand the sources that you use beyond scholarly or peer-reviewed journals into credible blogs, newspapers, trade publications, web resources, and others. The trickiest part is determining which are credible and which are fluff. The information below will help you make these determinations. This is not easy. You need to be vigilant, you need to think through where each source comes from, who wrote it, why did they write it, what means you can trust it.
The information and tests below will help you make that determination, but remember you also have experts that can help - your librarians and your professors.
Who wrote it?
How can I confirm what they are saying?