One of my favorite authors is Derek Prince. He has recently passed away, but his writings and messages are deep and profound! One of my favorite books by this Christian author is called:
"The Grace of Yielding"
Another excellent book is:
"Blessing or Curse: You Can Choose!"
He discusses how spoken words can have a profound effect in our lives. He provides solid biblical examples to illustrate his message, giving reminders from scriptures, where the Bible clearly teaches us to "guard our tongues".
The home page is: http://www.derekprince.org
http://www.derekprince.com/ (global websites)
His credentials are impressive, and he is a well-respected biblical scholar. His outreach is interdenominational. May it be a blessing to you!