An extensive mathematics reference service from the makers of Mathematica.
Finding Data
These are just a few of the resources you can use to locate research data. Guidelines for citing data sets vary; see specific data resources for more information about citations.
Figshare is a web service that makes data "citable, searchable, and shareable." Research data in a variety of formats is freely available through the figshare search tool and is protected under a Creative Commons copyright license.