But cf. - sustany/dvg GitHub Wiki

But cf. is a�signal�indicating that the cited source supports something similar to the opposite of the claim (proposition) just made by the author.�In other words, the cited source probably conflicts with the author's claim.�But cf. is the weakest of the major negative signals.

But cf. serves as the inverse of cf. Just as cf. precedes a source that supports a claim (proposition) different from the original claim but analogous to it, but cf. is used before a source that supports a claim that is different from the contrary claim but analogous to that contrary claim.

See also: order of signals