SAGE is free and open software that supports research and teaching in algebra, geometry, number theory, cryptography, etc. SAGE includes the following software: GAP, Maxima, Singular, PARI, MWRANK, NTL, Numeric, Python, IPython
Citation:
@artcle{SAGE,
key = "SAGE",
author = "William Stein and David Joyner",
title = "{SAGE: System for Algebra and Geometry Experimentation}",
year = 2005,
volume = 39,
number =2,
journal = "Communications in Computer Algebra",
}