Kox, Henk L.M.; Leeuwen, George van and Wiel, Henry van der (2010): Competitive, but too small - productivity and entry-exit determinants in European business services. Unpublished.
Kox, Henk L.M.; Leeuwen, George van and Wiel, Henry van der (2007): Market structure, productivity and scale in European business services. Unpublished.
