The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU02005977
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Number At Work 1 to 34 Hours, Usually Work Part Time Noneconomic Reasons [LNU02005977], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNU02005977/, September 2, 2015.