Start with high-confidence conflict resolution books, then narrow by subgenre or adjacent topics.
Verbal Judo, Second Edition
George J. Thompson, PhD
Getting to Yes
Roger Fisher, William L. Ury
Crucial Conversations: Tools for Talking When Stakes Are High, Third Edition
Joseph Grenny, Kerry Patterson
Can We Talk?
Roberta Chinsky Matuson
The First-time Manager: Leading Through Crisis
Paul Falcone
Little Book of Conflict Transformation
John Lederach
How to Untie a Balloon
Ryan Dunlap, Kwame Christian