The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU02026634
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Multiple Jobholders, Hours Vary On Primary Or Secondary Job [LNU02026634], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNU02026634/, September 4, 2015.