Michael Codish Dennis Dams Gilberto Filé Maurice Bruynooghe On the Design of a Correct Freeness Analysis for Logic Programs. 181-206 1996 28 J. Log. Program. 3 db/journals/jlp/jlp28.html#CodishDFB96 http://dx.doi.org/10.1016/0743-1066(95)00120-4