Here is by Dr. Charles Colin’s Complete Advanced Lip Flexibilities (Including Volumes 1, 2 & 3). This book is by far the most widely used trombone lip flexibility book in the world. This series of outstanding exercises was developed to enhance range, flexibility, and endurance. The studies are progressive in difficulty and take the student in moderate stages through basic warm-up procedures to exercises covering spreading intervals, expanding range, and lip trills. With the text completely reset and edited in 1980, this beautiful digital edition is a perfect update on a book that must be in every trombone player’s library.
You can view and play the samples provided here, then grab 9 x 12 physical book above.