Appendix A, Sources and Methods, Human Capital: A Theoretical and Empirical Analysis with Special Reference to Education, Third Edition

Gary S. Becker, Human Capital: A Theoretical and Empirical Analysis with Special Reference to Education, Third Edition (The University of Chicago Press, 1994), https://www.nber.org/books-and-chapters/human-capital-theoretical-and-empirical-analysis-special-reference-education-third-edition/appendix-sources-and-methods-human-capital-theoretical-and-empirical-analysis-special-reference.