What if the material is accurate and can be checked with a quick google search?
The burden of proof is always on the person adding the information.
"Source" does not mean "somewhere which can be used to verify the information", it means "the place where the information came from". Only the person that added the information actually knows the source, so they should be the one citing sources. The whole idea of adding sources to existing articles is completely backward. We need to work on getting people to actually *use* reliable sources, not just cite them. If people were actually using the sources then they could cite them as they went along with almost no additional work.