"Cf."

"cf." is the abbreviation for the Latin word confer or conferatur, which both mean "compare". A common usage error is to use "cf." when "see" or "see also" is appropriate; "cf." should only be used to suggest a comparison, not simply to indicate another source.

Correct usage: The text before the citation is contrasted with the work cited after "cf." Example: "...while theory supports the claim (cf. Jones 1992)." Example: "...the shield lacked the 'umbo,' the metal-boss of Waltharius (cf. lines 772 and 776)."

Incorrect usage: Using "cf." to mean "see" or "see also" is considered an error.
Incorrect: "...while theory supports the claim, see also Jones 1992."
Correct: "...while theory supports the claim (see also Jones 1992)."

"Cf." should not be followed by a comma. It is generally followed by a semicolon or parentheses, not a comma, when introducing citations that are meant to be contrasted.

Punctuation: If using multiple citations after "cf.", a semicolon is used between them, not a comma. Example: "...the claim (cf. Jones 1992; Smith 2003)."

The use of parentheses is common with "cf." citations.

In Numismatic use, the abbreviation can have a similar meaning in discussing literature or opinions, or it can be used in references on the paper and/or online coin identification information to mean "comparable TO". It is common for abbreviations of listings in coin catalogues or sales from certain online auctions to be cited when identifying a particular coin as a duplicate copy of the same coin (for example a die-linked coin). If the specimen in question being described is not an exact match but comes close to a known source, "cf." may be used in the meaning "comparable/similar to".