Cf. is an abbreviation of the Latin word confer, which means “to compare”. Cf. is a signal that the cited source supports a different statement (statement) than the one just made, that it is worth comparing the two claims and judging the difference. Explanations in parentheses are recommended to explain how a source relates to the text. In other words, a cf. source simply offers a different but not contradictory statement, and the actual support for the statement that has just been made should not be assumed. If the source makes a contradictory claim, a negative signal should be used.
