A primary source is a document or other sort of evidence written or created during the time under study or by one of the persons or organizations directly involved in the event. Primary sources offer an inside view of a particular event.
In science, we tend to see this as Original Research Articles, but it may also take other forms. For more examples check out the Types/Examples tab.
Below are examples of the kinds of formats you might find scientific primary sources in. Please remember that the guiding factor here is ORIGINAL RESEARCH.