Ravi Sen Chandrasekar Subramaniam Matthew L. Nelson Open source software licenses: Strong-copyleft, non-copyleft, or somewhere in between? 199-206 2011 52 Decision Support Systems 1 http://dx.doi.org/10.1016/j.dss.2011.07.004 db/journals/dss/dss52.html#SenSN11