I think we should caution students about sources ( I tell my students
how a fellow TA at UNM wrote himself in as the author of the Bible to
show his class why Wikipedia is unrealiable), but not deduct for
quality sources until the next draft. Students were on a fairly tight
schedule and learning how to use scholarly and credible sources can
take some time. At least in my class, I'm planning to dedicate a
portion of another class meeting to further discussion of sources.
Hope this helps answer your question (at least for the students in
Section 31).
-katie