Luisanna Cocco Katiuscia Mannaro Giulio Concas Michele Marchesi Study of the Competition between Proprietary Software Firms and Free/Libre Open Source Software Firms Using a Simulation Model. 56-69 2011 ICSOB http://dx.doi.org/10.1007/978-3-642-21544-5_6 conf/icsob/2011 db/conf/icsob/icsob2011.html#CoccoMCM11