Mathematical Reviews can be cited like any other journal, with a review number instead of volume and page numbers:

J. Smith.  Review of the article “Regular doodads are widgits” by J. Doe.  Mathematical Reviews **123456** (2009).

```
@article {review,
    AUTHOR = {Smith, J.},
    TITLE = {Review of the article ``{R}egular doodads are widgits'' by {J}. {D}oe},
    JOURNAL = {Mathematical Reviews},
    VOLUME = {123456},
    YEAR = {2009},
    ISSN = {0025-5629},
    URL = {https://mathscinet.ams.org/mathscinet-getitem?mr=123456},
}
```