Books: Emacs

• GNU Emacs Manual: Version 20.1, by Richard M. Stallman
  
  
• Learning GNU Emacs Manual by Cameron, Rosenblatt and Raymond, O'Reilly.
  
  

Online

• Xemacs - Manual
• Minimal Emacs Summary
• Emacs Reference Card in gziped postscript (ps.gz)
• Emacs Reference Card in pdf format
• info emacs
  man emacs
  /usr/share/doc/packages/emacs/doc