Cf.
A Latin citation abbreviation for confer, 'compare' — used to point the reader to a related passage.
Cf. is the abbreviation of the Latin imperative confer, 'compare'. In footnotes and parenthetical references it signals: the reader who wants to think further about this point should also look at the following source, which offers a related, contrasting, or corroborating view. It is not the same as 'see', which points to the source that supports the claim; cf. points to the source that will refine or challenge it.
The distinction matters. 'See Grafton 1997, 33' tells the reader: my claim is supported here. 'Cf. Grafton 1997, 33' tells the reader: my claim is worth reading alongside Grafton's, whose treatment is related but not identical. A reader who confuses the two will misread the argument.
Cf. is compact and useful precisely because there is no elegant English equivalent. 'For a related but different view, see…' says the same thing in eight words. In dense footnotes, the two-letter Latin saves a great deal of space over a long book.
Common mistakes: using cf. as a hedged 'see' when the writer is not sure whether the source really supports the claim; using cf. to point the reader towards a source that plainly contradicts the argument without saying so — that reads as evasive; and italicising the abbreviation, which is now considered unnecessary in most style guides.
“The footnote is often called an early modern invention (cf. Grafton 1997, ch. 1, who traces it earlier).”
Keep reading the glossary
A citation shorthand meaning 'in the same source as the previous note'.
A citation shorthand meaning 'in the work already cited'.
Latin for 'and others' — used in citations of multi-author works.
Latin for 'thus' — used in quotes to mark an error reproduced from the original.