http://www.ams.org/mcom/2002-71-240/S0025-5718-01-01390-4/home.html
http://www.gap-system.org
http://www.singular.uni-kl.de
http://pari.math.u-bordeaux.fr/
.
http://modular.math.washington.edu/sage/
http://sage.sourceforge.net/
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