Scientific and other peer-reviewed journals are excellent sources for primary research sources. However, not every article in those journals will be an article with original research. Some will include book reviews and other materials that are more obviously secondary sources. More difficult to differentiate from original research articles are review articles. Both types of articles will end with a list of References (or Works Cited).
Review articles are often as lengthy or even longer than original research articles. What the authors of review articles are doing is analyzing and evaluating current research or investigations related to a specific topic, field, or problem. They are not primary sources since they review previously published material.
They can be helpful for identifying potentially good primary sources, but they aren't primary themselves. If it is a review article instead of a research article, the abstract should make that clear. If there is no abstract at all, that in itself may be a sign that it is not a primary resource.
Sometimes, it is easier to find a Review Article, and then work backwards to the Primary Sources that are being reviewed. The Review Article can also provide valuable insight on the state of knowledge in a particular field.
A Primary Source is an original document or item. It is the raw material or first-hand information. In the Natural Sciences (Biology, Chemistry, etc.), the results of an experiment are considered raw data. Therefore, journal articles that present this original raw data are considered Primary Sources.
Primary Research Articles can usually be identified by a commonly used format. If the article contains the following elements, it is usually a Primary Source Document.
Sometimes a short research article will not contain these separate components. In this case, look at the wording used. Phrases such as "we tested", "we used",& "in our study, we measured" will usually tell you if original research is being reported.
A secondary source is something written about a primary source. Think of this as second-hand information. Secondary source materials can be articles in newspapers or popular magazines, book or movie reviews, or articles found in scholarly journals that evaluate or criticize someone else's original research.