A Proposal to Add Hash Tables to the Standard Library
http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1456.html
The hash table proposal explains much of the design. The hash function object is discussed in Section D.

The C++ Standard Library Technical Report.
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1745.pdf
Contains the hash function specification in section 6.3.2.

Library Extension Technical Report Issues List.
http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
The library implements the extension described in Issue 6.18.

Methods for Identifying Versioned and Plagiarised Documents
Timothy C. Hoad, Justin Zobel
http://www.cs.rmit.edu.au/~jz/fulltext/jasist-tch.pdf
Contains the hash function that boost::hash_combine is based on.