Ayal Z. Pinkus Serge Winitzki YACAS: A Do-It-Yourself Symbolic Algebra Environment. 332-336 2002 conf/aisc/2002 AISC http://link.springer.de/link/service/series/0558/bibs/2385/23850332.htm db/conf/aisc/aisc2002.html#PinkusW02