Who wrote it? What could their biases and affiliations be?
What kind of source is it? A book? A newspaper article?
What claims does the source make? What is its argument or thesis?
Where was it published? In an encyclopedia? Online? What country?
When was it written? What time frame does it cover?
Why did the author write it?
Why might it be useful to my own argument or research questions?
The Perfect Source? Not Likely
Research isn't about finding that one perfect source that makes all the connections for you.
It's about pulling together information that helps you formulate your ideas and make the argument yourself. This video (2 minutes) explains why finding one perfect source isn't feasible, and describes some ways you can be strategic about your searching.