Who is the author?
Is the author a researcher, clinician, a government, organization or corporation?
Publication date of the source?
Depending on research field, publication date may indicate if the source is up to date or not.
Who is the intended reader?
The language used in the text may reflect the intended reader- e. g. many research terms or simplified language? Students, researchers or public?
What is the purpose or intention of the source?
Is it to communicate research results or is the purpose to influence opinion?
Who is responsible for the information and facts?
Is it a university, a research group, an organization, a corporation or individual?

Are there references to facts and previous research?
A research article always have references to previous research and relevant background facts.
Are there additional sources?
Can you find additional sources that confirm or contradict the source, or that gives additional perspectives to the source?