Where can I read about the life of Earl Nightingale

Hello,

I admire Earl Nightingale, the "dean of self-improvement". On trying to find information on his personal life, however, I have been almost entirely unsuccessful; But I feel that this is important for gaining a better understanding of what "made the man tick".

I read most of his books and heard most of his tapes. Only very rarely does he drop the slightest morsel of REAL personal information, such as that he was married three times.

I have also read Diane Nightingale's book "Learning to fly like a nightingale" (Diane must be his third wife), but she seems to black out important information on Earl's personal life before he married her.

Any clues on where I might be able to find something more profound in this area? Perhaps some web links, or obscure books?

Thanks.
Wolfgang