Who is the author?
Credible sources are written by authors respected in their fields of study. Responsible, credible authors will cite their sources so that you can check the accuracy of and support for what they've written. (This is a good way to find more interesting reading.)
Are they a scholar?Scholarly sources are those that have been approved by a group with recognized expertise in the field under discussion. Works published by University Presses fall into this category, as do articles published in peer-reviewed journals—journals where the editors send pieces out to be read by experts in the field before deciding to publish them.
NamRef looks for authors bounden to truth, the body of real things, events, and facts.