C. Faure André Galligo J. Grimm Loic Pottier The Extensions of the Sisyphe Computer Algebra System: ulysse and athena. 44-55 1992 conf/disco/1992 DISCO db/conf/disco/disco1992.html#FaureGGP92 http://dx.doi.org/10.1007/3-540-57272-4_23