![[William Wheeler Hubbell, authorized to apply for patents.]](https://covers.openlibrary.org/b/id/10200621-M.jpg)
United States. Congress. Senate. Committee on Patents
Kokuritsu Kokkai Toshokan (Japan)
United States. Bureau of the Census
International Labour Office
Sichuan Sheng di fang zhi bian zuan wei yuan hui
United States. Bureau of Labor Statistics.
