should never, therefore, be used on its own, which would be meaningless, but most often with the author's surname,[1] or another brief clue as to which work is referred to.
", usually followed by a page number, to refer the reader to a previous full citation of this work (or with further clarification such as "Smith 1999, op.
Given names or initials are not needed unless the work cites two authors with the same surname, as the whole purpose of using op.
For works without an individually named author, the title can be used, e.g. "CIA World Fact Book, op.
cit., an abbreviation of the Latin phrase loco citato meaning "in the place cited",[1] has been used for the same purpose but also indicating the same page not simply the same work; it is now rarely used or recognized.
The Chicago Manual of Style, 16th edition, claims that op.
[2] Various different styles call for other alternatives, such as a reference to the author's surname and publication year, e.g. "Smith 1999".
), the Latin definitive pronoun meaning "the same"[5] is also used on occasion (especially in legal writing) within footnotes, and is a stand-in for the last-cited author, rather than title.