Peace studies is a highly interdisciplinary field. EBSCO Cross-Search includes scholarly articles from 20 subscription databases (including Political Science Complete, Historical Abstracts, and Gender Studies Database), so it's a great starting point for your research.
A list of all CSB/SJU Libraries' databases is on the Databases A-Z page. Specific collections that might also be helpful for peace studies research include:
The Journal of Social Encounters (JSE) is an interdisciplinary online journal that publishes scholarly, peer-reviewed essays on peace, conflict, and social justice issues in any part of the world. It is published by CSJE at Catholic University in Eastern Africa in Nairobi, Kenya, in collaboration with the Department of Peace Studies at CSB/SJU.