In writing — notes, dictionaries, academic books — cf. (often with a full stop) puts another page, book, or example in front of you and asks you to compare it, or at least to consider it beside the point you just read. It does not mean “this is the same,” it does not mean “for example,” and it does not mean “copy this.” “See” points; cf. says “hold this next to that, and notice how they sit.” It comes from scholarly Latin and stays on the page. Nobody says “cf” across a café table.

參見、比較（寫作標記，不是「例如」）