Start with Copley Library, searching from the library home page.
While not synonymous, Catholic Social Teaching and Catholic Social Thought will both bring you results that have to do with Catholic Social Thought.
Place your terms in quotation marks to keep them together as a phrase: "Catholic Social Teaching"
And add more terms after that: "Catholic Social Teaching" and economics
Consider reference works like the Encyclopedia of Catholic Social Though, Social Science, and Social Policy.
Brainstorm alternative ways to phrase the themes you're interested in.
Think about a particular theme in reference to a specific issue. For instance, you may search for:
And keep in mind that adding Catholic or Catholicism may help you narrow your results
The Atla Religion Database contains multiple Catholic resources, including the Catholic Periodical Literature Index and the Catholic News Archive.
Search for the theme you're interested in - if you get too many results, add a narrower topic, like housing or migration or climate.
Sacred and Social: Theological Foundations for Catholic Social Teaching by Kenneth R. Himes
Catholic social teaching in practice: exploring practical wisdom and the virtues tradition by Andrew M. Yuengert
Living Justice :Catholic Social Teaching in Action by Thomas Massaro, SJ.
Christianity and agroecology by Matthew Philipp Whelan
Dwelling with dignity: Catholic Social Teaching and homelessness by Suzanne Mulligan
Catholic Social Teaching and Labour Law: An Ethical Perspective on Work by Mark Bell
Business Ethics and Social Responsibility: Essential Works of Fr. Gerald F. Cavanagh S. J.
Scholarly research is often synonymous with peer-reviewed research, but this is not always the case, especially when we research topics like Catholic Social Thought. Many scholars publish non-scholarly, aka popular, work on CST, for various reasons. These sources have the potential to reach wider audiences and therefore bring more people into conversation with the topic.
If you don't narrow your results to peer-reviewed, your results will include books and book chapters, which can also be scholarly - as well as newspapers and magazines, which are popular sources, and can be a great source of information about CST themes, especially Catholic newspapers and magazines.
The only thing to keep in mind is that popular sources may be written by authors from a variety of backgrounds and educational levels. Your experience with searching using Google or other web browsers will come in handy here, as simple research into an author's name should give you some information about their expertise in the subject area, and should help you decide whether to call the source in question a reliable one. Remember, reliability of sources depends on your topic, and your particular take on your topic.
See the United States Conference of Catholic Bishops for more on each of the seven themes:
Life and Dignity of the Human Person
Call to Family, Community, and Participation
Option for the Poor and Vulnerable
The Dignity of Work and the Rights of Workers