There is an excellent book on the rivalry called "Ghosts of Manilla" that is a rare assessment of the three fights, two fighters and the lasting impact that they had on the sport. It is the only thing I've read that didn't fawn over Ali as "The Greatest" and talked about how at the time of the first fight it was actually Ali that needed to fight Frazier to restore his stature after being barred from boxing for refusing to answer the call to the draft. Frazier gave Ali the shot out of loyalty to the former friend and Champ and Ali exploited his kind gesture by calling him and "Uncle Tom" among many other terrible things. It even claimed that Frazier supported Ali during his time out of the ring becuase Ali's handlers from the Nation of Islam were bleeding him dry. A great read that gives a far greater context to the rivalry than just their relative stats and legacies.
