Michael R.B. Keighley & Norman S. Williams 
Keighley & Williams’ Surgery of the Anus, Rectum and Colon, Fourth Edition [PDF ebook] 
Two-volume set

This fourth edition of Surgery of the Anus, Rectum and Colon continues to redefine the field, with its comprehensive coverage of common and rare colorectal conditions, advances in the molecular biology and genetics of colorectal diseases, and new laparoscopic techniques. Contributions from international experts on specialized topics and various new illustrations ensure that the extensive text is not only current and authoritative, but easy to understand. No other book provides the expertise of a world-class editorial team with the cutting-edge knowledge you need to master colorectal surgery.