The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNS13100000
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Unemployment Level: Looking For Full-Time Work [LNS13100000], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNS13100000/, September 4, 2015.