There is an exception to the rule against using reference footnotes for citing your sources. If you have many citations for one sentence (in other words, many sources for one piece of information), then you may use a footnote to avoid cluttering the text and disrupting the reader's attention to your reasoning.
For example:
and at the bottom of the page, put a footnote:
1. see Collins 1967:67; Crenshaw 1934:98; Morton 1978:81-89 & 1979:97.
This is better than an unlovely in-text citation such as: Beagles are fond of bagels (Collins 1967:67; Crenshaw 1934:98; Morton 1978:81-89 & 1979:97). In this case, using the reference footnote makes this easier to read without losing the sense of the text. The idea is to avoid doing anything to distract the reader's attention from what you have to say. Unless an idea is very complex or profound --like Beagle bagelphilia- or the data very technical or surprising, you rarely need to use many citations for one particular chunk of information. A single citation will generally do.
Footnotes should go at the bottom (foot) of the page. Some publishers put them at the end of the book. They claim this saves typesetting money (although with computerized typesetting that is no longer true). The real reason is that they hate readers. In any event, term paper footnotes should go at the bottom of the page. It not only keeps the professor from cursing your future posterity as he fumbles his way to the back in search of a note, it also improves the chances that he will actually pay attention to them. (Nothing is more infuriating, by the way, than to make one's way to the back of the book in search of footnote 73 from chapter fourteen only to find that it says "op cit" in reference to something last discussed six chapters earlier.)
