If you refer to a particular subject or person, you mention them.
If you refer to someone or something as a particular thing, you use a particular work, expresson, or name to mention them.
2011-06-15 13:45:03 補充：
更正：a particular word誤打成a particular work
2011-06-16 13:43:08 補充：
refer to xxx 與mention xxx 是可以互換,意思相同的,但在後面有as時,用法不同.
Collins Cobuild English Dictionary for Advanced Leaners 3rd edition