These are some of the best books that include information about the Pilots:

Hardball: The Education of a Baseball Commissioner
Bowie Kuhn. Times Books, 1987.
The best insider's account of the Pilots' move to Milwaukee. Former American League president Lee MacPhail mentions it in his autobiography, My Nine Innings, but very briefly.

The Lords Of Baseball
Harold Parrott. Praeger Publishers, 1976.
Parrott was a long-time Dodgers employee and knew many of the biggest names in baseball. For a short time, he was the Pilots' Director of Sales and Promotion and spends a good chunk of his book blasting team president Dewey Soriano.

Endless Summers: The Fall & Rise of the Cleveland Indians
Jack Torry. Diamond Communications, 1996.
Excellent background on the baseball career of Pilots owner William Daley and simply a top-notch baseball book. A great read even if you're not an Indians fan.

The Seattle Pilots Story
Carson Van Lindt. Marabou Publishing, 1993.
A well-done chronicle of the Pilots' on-field history, with a concise history of Seattle baseball and some background on the behind-the-scenes action.

Off the Record
Buzzie Bavasi with John Strege. Contemporary Books, 1987.
Before Seattle joined the American League, Bavasi was virtually guaranteed a National League franchise for the area. He touches on that only briefly, but gives an interesting account of the early days of the San Diego Padres.

Ball Four
Jim Bouton. Dell, 1971.
A baseball classic and the only contemporary record of the Pilots from the players' perspective. Unfortunately, Bouton was traded to the Astros before season's end, so we never got his take on the off-field dilemmas.