Never use cf. in the meaning of "see"
If a footnote refers to the same source as the one referred to in the footnote immediately preceding, the abbreviation ibid. (form Latin ibidem) may be used. If the volume, page, title, and author are the same, use ibid. alone. If the volume and page differ, use, for example, ibid., III., 206. Ibid usually comes at the beginning of a footnote and is capitalized for that reason only.
If the reference is to the exact passage covered by an earlier reference not immediately preceding, use loc. cit. (from Latin loco citato). Never follow loc.cit. with a page number. Many instructors and editors believe that loc.cit. and op.cit. are the most abused and overused of all abbreviations in research writing; they advocate, instead, the author's name alone with a short title for footnote references after the first.
Used in brackets in a quotation to show that the material preceding has been followed exactly, even if there is an obvious factual error or an error in spelling, grammar, punctuation, or word used.