MathWorld"MathWorldTM is the web's most complete mathematical resource, assembled over more than a decade by internet encyclopedist Eric W. Weisstein with assistance from the mathematics and internet communities. MathWorld is a comprehensive and interactive mathematics encyclopedia intended for students, educators, math enthusiasts, and researchers." The site is searchable or there is an index available by broad topics such as algebra, applied mathematics, etc. or a more specific alphabetical index.