For All the Saints
- Short biography of Pope St. Symmachus.
- http://www.saintpatrickdc.org/ss/0719.htm#symm

The Ecole Glossary
- The turbulent first five years of the pontificate of Pope Symmachus.
- http://www2.evansville.edu/ecoleweb/glossary/symmachusp.html

Popes Through the Ages
- Short biography of Pope St. Symmachus, from the book by Joseph Brusher.
- http://www.cfpeople.org/Books/Pope/POPEp51.htm

Catholic Encyclopedia
- Lengthy article on Pope St. Symmachus, who died in 514.
- http://www.newadvent.org/cathen/14377a.htm