"Sources are people talking to other people." Doug Downs
Who wrote it? A journalist? An academic scholar? A person who has expertise of some sort?
When was it written? What effect does its age or currency have on its value to you?
Why was it written? What audience did the author have in mind? What are they trying to do with this document - persuade, inform, further our knowledge by publishing new research findings?
Where did they get their information? What evidence do they present? Do they explain the sources of their information?
How did they arrive at their conclusions? Did they use appropriate methods to get there? Did they misunderstand anything or leave something important out?
What have other people said about this topic? How does this source fit in with the larger conversation?
Sources have different functions for your research (BEAM)
There are different authors of information
There are different audiences for publications
There are different packages for information