Based on the CRC Encyclopedia of Mathematics by Eric W. Weisstein, take advantage of the nested topics at the top, and the See Also links, and references at the bottom.
Based on the online Encyclopaedia of Mathematics, which was written as a graduate-level math resource and published by Kluwer Academic Publishers. It has since developed into an wiki for the online math community.
Videos on pre-algebra, geometry, trigonometry, calculus, probability, statistics, and linear algebra.
Library Books
The Cambridge Dictionary of Statistics by B. S. Everitt; Anders SkrondalIf you work with data and need easy access to clear, reliable definitions and explanations of modern statistical and statistics-related concepts, then look no further than this dictionary. Nearly 4000 terms are defined, covering medical, survey, theoretical, and applied statistics, including computational and graphical aspects. Entries are provided for standard and specialized statistical software. In addition, short biographies of over 100 important statisticians are given. Definitions provide enough mathematical detail to clarify concepts and give standard formula when these are helpful. The majority of definitions then give a reference to a book or article where the user can seek further or more specialized information, and many are accompanied by graphical material to aid understanding.