Periodicals can be classified into two types: popular and scholarly. The popular periodicals are magazine and newspapers, like Ebony and Esquire. The scholarly periodicals are found in libraries and databases. Examples are The Journal of Psychology and the Journal of Social Work. Trade/Professional journals are also examples of periodicals. They are written for an audience of professionals in the world. As of the early 1990s, there were over 6,000 business, technical, academic, scientific and trade publications in the United States alone.