OK, fine. The next two Amazon books I get for "programming interview", "Elements of Programming Interviews" and "Programming Interviews Exposed", both have three authors each. In both cases, only one of the authors is actually employed as a programmer. The others include an EE professor, a radiologist and two executives. The field is rife with non programming authors.

"I wrote a book about programming interviews" does not signal to me that you are, in fact, a programmer.

I am happy to believe Gayle is a programmer, but I wouldn't use her book as a credential to support that claim.

(And I just realized that I'm replying to Gayle. I didn't read your username before posting. oops. The "you" above wasn't meant to be directed at you personally.)