These links to a variety of study centers and academic associations contain many additional links and resources and are the source for some of what this guide contains.

Augustinian Institute (Villanova University)

http://www1.villanova.edu/villanova/mission/augustinianinstitute.html

Center for the Study of Early Christianity (Catholic University of America)

https://arts-sciences.catholic.edu/academics/interdisciplinary/early-christianity/index.html 

Centre for Early Christian Studies (Australian Catholic University)

http://www.cecs.acu.edu.au/

International Association of Patristic Studies

https://www.aiep-iaps.org/

North American Patristics Society (Resources page)

http://www.patristics.org/news-item/resources/

Pappas Patristic Institute (Research Center at Holy Cross Greek Orthodox School of Theology)

http://www.hchc.edu/patristics/

Robert C. Cooley Center for the Study of Early Christianity (Gordon-Conwell Theological Seminary)

http://www.gordonconwell.edu/resources/cooley-center.cfm

Southwestern Center for Early Christian Studies

https://earlychristianstudies.org/

The Wheaton Center for Early Christian Studies https://www.wheaton.edu/academics/school-of-biblical-and-theological-studies/the-wheaton-center-for-early-christian-studies/