When writing for academic purposes, while scholarly peer-reviewed journal articles are considered the gold-medal standard for research sources, it is important to know not all journal articles are created equally.
While most journal articles are produced by reputable publishers who recognize, and critically appraise, ethically sound research, some online scientific journals are willing to publish any form of research as long as the author is willing to pay a fee. See the story published by the Ottawa Citizen for their expose on predatory journals.
Furthermore, even when articles are published by credible organizations that peer-review each submission, a new Canadian study found that sometimes the editors and reviewers of medical journals accept articles that contain references to secondary sources, like Wikipedia.
While primary sources are considered to the most reliable type of source used, in order to validate the information others have published on their behalf, online groups like the Wiki Project Med Foundation, and the Cochrane Collaboration’s Wikipedian in residence program are providing a new sort of peer review process for information posted to Wikipedia.