Polder, Michael; Veldhuizen, Erik; Bergen, Dirk van den and Pijll, Eugène van der (2009): Micro and macro indicators of competition: comparison and relation with productivity change. Unpublished.
Polder, Michael; Van Leeuwen, George; Mohnen, Pierre and Raymond, Wladimir (2010): Product, process and organizational innovation: drivers, complementarity, and productivity effects. Unpublished.
Polder, Michael; Leeuwen, George van; Mohnen, Pierre and Raymond, Wladimir (2009): Productivity effects of innovation modes. Unpublished.
