J. Henkel, and S. Pangerl. DRUID Working Papers, 08. DRUID, Copenhagen Business School, Department of Industrial Economics and Strategy/Aalborg University, Department of Business Studies, (2008)
A. COWELL, and J. GREENBERG. http://ezproxy.library.wwu.edu/login?url=http://proquest.umi.com/pqdweb?did=119190033&Fmt=7&clientId=9320&RQT=309&VName=PQD, (May 2002)