There's a great interview on by Keith Elliot Greenberg on WWE.com with former referee Dick Kroll, who may be the only official to work title matches for the big three (WWWF, NWA and AWA) in the same year.
It's a valuable window into a time when wrestling fans were really passionate about the sport, like Kroll's recounting of the 1972 Shea Stadium spectacle between Bruno Sammartino and Pedro Morales:
There was a lot of ethnic tension. When I walked through the parking lot before the match, the Italians recognized me and said, ‘Bruno better not lose.’ Then, the Puerto Ricans said, ‘Pedro better win.’ Fortunately, it was a draw. And when Bruno and Pedro hugged, and waved the American, Italian and Puerto Rican flags after the match, the tension went away. Everyone was united.