One of the purposes of librarians is to help refer people to authoritative sources. When the bulk of “sources” were printed books, we could usually be assured that the editors and publishers performed a large amount of the vetting for us, and often reviewers and the opinions of other librarians or professionals would fill in the blanks in the cases of problems or questions. Online and/or open source versions of reference sources — which can change on the fly, and lack many of the markings we traditionally associate with authority — have become a new question mark in the world of librarianship, addressing the question “what is an authoritative source?” Jessica has been going over this on her scratchpad lately, most recently discussing this experiment in which deliberate misinformation was put into Wikipedia to see if it stayed. Upshot? The changes were replaced within hours. Does this prove that the Wikipedia is authoritative? Not necessarily, but it’s one more data point explaining how the system works to people that aren’t familiar with it, and one more data point to use with naysayers who think that having a resource be freely editable means that by definition it can’t also be authoritative.