I am often asked for references of the books I use in my practice and teaching. I have added a non-exhaustive list of reference books for mediation and negotiation below, in no particular order.

Negotiation Excellence: Successful Deal Making, 2nd Edition By Michael Benoliel.
Getting to Yes: Negotiating Agreement Without Giving In Hardcover- April 30, 1992 by William L. Ury, Roger Fisher, Bruce M. Patton
Getting Past No: Negotiating in Difficult Situations Paperback – January 1, 1993 by William Ury
Beyond Winning: Negotiating to Create Value in Deals and Disputes Mnookin, Robert H.
Bargaining with the Devil: When to Negotiate, When to Fight Robert Mnookin.
The Negotiator’s Fieldbook: The Desk Reference for the Experienced Negotiator Paperback – November 6, 2006 by Andrea Kupfer Schneider and Christopher Honeyman
The Art of War by Sun Tzu
NEGOTIATION Things Corporate Counsel Need to Know but Were Not Taught by Michael Leathes
3-D Negotiation: Powerful Tools to Change the Game in Your Most Important Deals by David A. Lax, James K. Sebenius
Getting to Yes with Yourself (and Other Worthy Opponents) by William Ury
The Power of a Positive No: Save The Deal Save The Relationship and Still Say No by William Ury
PON (Harvard) Negotiation Journal