¹ Most of the data on American higher education in this book are from the Digest of Education Statistics of the National Center for Education Statistics, U.S. Department of Education (http://nces.ed.gov/); U.S. Statistical Abstracts of the U.S. Census Bureau (http://www.census.gov/compendia/statab/); and the Carnegie Foundation for the Advancement of Teaching (http://www.carnegiefoundation.org/). In my citations, I give the source of my data, but I generally do not provide specific urls, since these change as databases are updated.