Charles-Louis Hanon
"Exercise Twenty (Extension of 2-4, 4-5, and exercise for 2-3-4)"
Overview
Extension of 2-4, 4-5, and exercise for 2-3-4. End of Part I. After having mastered this First Part, play it through once or twice daily for some time before commencing the study of the Second ("transcendent") Part; by so doing, one is sure to obtain every possible advantage that this work promises. Complete mastery of Part I gives the key to the difficulties found in Part II.（Source）
