Sage Quick Reference Cards
Sage Quick Reference by William Stein (March 2009) - quickref.pdf (and the source quickref.tar.bz2)
Sage Calculus Quick Reference by William Stein (April 2009) - quickref-calc.pdf (and the source
Basic Math by Peter Jipsen, version 1.1 (January 2008) - sage-quickref.pdf (sage-quickref.tex)