Columbia subject headings:
Industrial productivity--United States--Mathematical models.
Research, Industrial--United States--Mathematical models.
Technological innovations--Economic aspects--United States--Mathematical models.
Harvard subject headings:
Industrial productivity--United States--Mathematical models.
Research, Industrial--United States--Mathematical models.
Technological innovations--Economic aspects--United States--Mathematical models.
Princeton subject headings:
Industrial productivity--United States--Mathematical models.
Research, Industrial--United States--Mathematical models.
Technological innovations--Economic aspects--United States--Mathematical models.