Jack Dempsey was one of the most incredible combatants to ever live. Long before he entered the professional ring he fought in hobo jungles, freight yards, and saloons. He recorded in meticulous notes, advice and techniques from all of his fights and advice from his trainers. He wrote a book on boxing, which can be downloaded as a .PDF or Text file, here

He also wrote a book on self defense, How to Fight Tough, which can be bought, here
His record only includes his professional fights. Not his bareknuckle career that may have been up to 100 fights.

Boxing record
Total fights 83
Wins 62
Wins by KO 50
Losses 6
Draws 9
No contests 6 [1]

Here is his dismantling of Giant Jess Willard. One of the most brutal bouts of all time.