Zacharius Ursinus
- Biographical article in New Schaff-Herzog Encyclopedia of Religious Knowledge.
- http://www.ccel.org/ccel/schaff/encyc12/Page_111.html

What is The Gospel?
- Online book by Ursinus.
- http://www.ccel.org/ccel/ursinus/gospel.toc.html

Justification by Grace Alone Through Faith Alone
- From his Commentary on the Heidelberg Catechism, specifically Questions 59 and 60.
- http://www.truecovenanter.com/gospel/ursinus_justification.html

Ursinus and Olevianus
- Biographical articles on both reformers.
- http://www.prca.org/books/portraits/ursinus.htm

Ursinus on Worship
- From Ursinus' Commentary on the Heidelberg Catechism, specifically on Question 96.
- http://www.apuritansmind.com/PuritanWorship/ZachariasUrsinusOnWorship.htm

Catechisms of Ursinus
- The large and small catechisms written by Ursinus compared in a three column format with the Heidelberg Catechism, written by Ursinus and Olevianus.
- http://www.christreformed.org/doctrinevision/ursinus_project.pdf