By Compound Interest: http://www.compoundchem.com/2014/04/02/a-rough-guide-to-spotting-bad-science/
Are original research and include details of the scientific data obtained during the research, and should specify the methodology used in the study. They are known as a primary source of scientific information, and should include:
Review the literature published on a particular topic:
A review article is usually considered to be a secondary source of information, and can provide a great starting point for researching a topic. The reference list is a good way of locating other literature that may be relevant to your topic- citations for the research articles (primary sources) discussed. Be aware that a review article reflects the view/bias of its authors - you should still look at the articles discussed and draw your own conclusions.
Take notes on the articles as you read them and identify any themes or concepts that may apply to your research question.
This sample template (below) may also be useful for critically reading and organizing your articles.