re: Do you consider Wikipedia a credible source?

It can be, and usually is at least solid for getting accurate facts and statistics. For description of historical or political events, however, it should be used with a very critical mind. I've read things that were either inaccurate or unsupported on there before. But it is not a source of information that I would immediately discredit as providing valid support for one's ideas like I so often see people claiming. But even though it lists references, you can't verify that the information provided is true to the sources since it isn't peer reviewed and can be edited by anyone at any given time. So really you would have to check those sources yourself.

It's very valuable as a guide to quickly learn the background of any number of things, but I seek to avoid using it as support for any argument. Of course academically I would never use it. However, it can be a great place to lead you to legitimate sources by checking it's listed references.