The NBER-Rensselaer Scientific Papers Database: Form, Nature, and Function
NBER Working Paper No. 14575
---- Acknowledgements ----
The Andrew W. Mellon Foundation has generously supported this research. We thank Nancy Bayers and Henry Small of Thomson-Reuters for assistance with the data that we describe in this article. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.