Popular
publications inform and entertain the general public. Magazines like Time and Rolling Stone and books like Michael Jackson : Music's Living Legend by Rosemary Wallner, distributed by Rockbottom Books, are examples of popular sources.

Scholarly
publications disseminate research and academic discussion among professionals within disciplines. Journals such as Memory & Cognition and Journal of Abnormal Psychology are examples of scholarly sources.

Trade
publications which are neither scholarly nor popular sources, though sometimes are a combination of both, allow practitioners in specific industries to share market and production information that improves their businesses.