is a good starting point for books
A search for Healthcare and UNITED STATES produces 2196 hits
A search for "health care" "united states" produces 13910
Here is one to try
Subject-specific databases are the most comprehensive. By using “controlled vocabulary”—a thesaurus—you can do a more efficient search than typing “Medicaid expansion” (or whatever your topic is) into Google, http://library.princeton.edu/ , JSTOR, Ebsco, or Proquest.
The “Databases” tab may be a good place to start instead of keyword searching in
Possibly relevant databases (all with thesauri)
Google Scholar on your text “Health disparities in the United States : social class, race, ethnicity, and the social determinants of health / Donald A. Barr.”
Limit by recent and/or covid
For 1878-1949, use the .
Collection of more than 2,000 current and historical data series allowing comparison and ranking of US states on a variety of topics. View data as graphs, charts, or tables, all of which can be easily exported; export an entire series by saving an item to the Data Cart. Most series cover mid-1990s to present.
Bibliographic index to publications in statistics and related fields. References are drawn from 162 core journals (as of 2003) that are fully indexed, non-core journals from which articles are selected that have statistical content, proceedings and edited books, and other sources.