TITLE: Is there a sign for "according to?"
QUESTION [5 upvotes]: There are signs in mathematics for "therefore" and "because," which are $\therefore$ and $\because$ respectively.
However, another frequently-used expression is "according to." Is there any symbol for that?

REPLY [2 votes]: There is a Latin abbreviation sec. from secundum, meaning "following" or "in accordance with", sometimes used as "sec. Smith", which means "according to Smith".