http://www.simon.rochester.edu/fac/misra/mkt_salesforce.pdf.

Barry Gruenberg, “The Happy Worker: An Analysis of Educational and Occupational Differences in Determinants of Job Satisfaction”, American Journal of Sociology 86 (1980), pp. 247–71, esp. pp. 267–68, in Kohn, Punishment by Rewards, p. 131.