The phrase "as stated" is typically used to refer to something that has been previously mentioned or stated. However, there are several other ways to convey the same idea. For example, one could use "according to," "as indicated," "as noted," "as declared," or "as mentioned." All of these options convey the same idea, that the information being discussed has been previously stated or referred to. Varying one's language can increase variety and interest in writing, and using synonyms can prevent repetition and keep readers engaged. No matter what synonym is used, the important thing is to ensure that the message is clear and easily understood by the reader.