"Previously mentioned" is a commonly used phrase used to refer back to a topic or statement that has already been discussed. However, there are several other synonyms that can be used instead of this phrase. Some of these synonyms include aforementioned, aforementioned above, earlier mentioned, previously discussed, previously stated, previously brought up, before-mentioned and already referenced. These synonyms can add variety to writing, making it more engaging and less repetitive. Using synonyms also helps readers to follow the flow of the text and keeps them engaged by avoiding monotony. Therefore, it's important to use synonyms in writing, to add variety and depth to the language while referencing previously discussed topics.