You have read the title. I have no doubt it has underwhelmed you. Nevertheless, if you are in one of my classes I teach, you are undoubtedly curious, and quite possibly anxious. For if a college or graduate school library goes down on courses that are, now, online, one has good reason to be concerned. For, I require, at least, two peer-reviewed articles for 5 pages of research. For a discussion on “why,” and related thinking, see my article on “A Taxonomy of Scholarly Sources” (https://michaelmilton.org/2019/06/21/a-taxonomy-of-references-in-writing-graduate-level-theological-papers/https://michaelmilton.org/2019/06/21/a-taxonomy-of-references-in-writing-graduate-level-theological-papers/).
I always encourage students to utilize their library resources, first. Your institutional library will have access to proprietary sources that will likely provide exactly what you need, usually with fewer clicks.m; Yet, sometimes those systems go down, or, for one reason or another, you lose access. In such cases, one has the opportunity to visit a number of good online databases. I will list a few of those.
There are many others out there though many are geared to STEM research. My list is focused on Theology and Religous Studies, and open access to a broad range of academic disciplines.
Any of these should be more than adequate in locating sources for the classes that I teach. Indeed, most of these will cover classes throughout our seminary curriculum.
I will rank these according to my own preference.
Global Scholarly Journal Searches (will list both open, and subscription services)
Theology and Religious Studies
Speer Library at Princeton Theological Seminary (outstanding): https://library.ptsem.edu/original-digital-library
Collections at Princeton Theological Seminary: https://commons.ptsem.edu
Puritian Reformed Theological Seminary Free Access Commons: https://prts.edu/library-overview/open-access-resources/
Duke University IntraText Digital Library: http://www.intratext.com/BRI/
Harvard Divinity School Digital Access: https://library.harvard.edu/digital-collections
Luther Seminary: https://digitalcommons.luthersem.edu/
Fuller Theological Seminary: https://digitalcommons.fuller.edu
Liberty Theological Seminary: https://digitalcommons.liberty.edu
Hope College: https://digitalcommons.hope.edu
Pepperdine University: https://digitalcommons.pepperdine.edu
Abilene Christian University: https://digitalcommons.acu.edu/dmin_theses/
Wofford College Digital Commons: https://digitalcommons.wofford.edu
Tyndale Seminary Digital Resources: https://libguides.tyndale.ca/c.php?g=315370&p=2107774https://libguides.tyndale.ca/c.php?g=315370&p=2107774