Undocumented DOS by Andrew Schulman, Ralf Brown,

http://www.awprofessional.com/title/0201570645?redir=1

Undocumented DOS: A Programmer's Guide to Reserved MS-DOS Functions and Data Structures/Book and Disk (Andrew Schulman Programming)
by Andrew Schulman, Ralf Brown, David Maxey, Raymond J. Michels

One of the most important books in the history of the PC industry.

http://www.amazon.com/exec/obidos/tg/detail/-/020163287X/qid=1119444376/sr=1-8/ref=sr_1_8/104-2402366-1295135?v=glance&s=books

http://www.undoc.com/

http://www.accu.informika.ru/accu/bookreviews/public/reviews/u/u001265.htm