She also went to the streets of Baltimore and met people like Skinny "Rim" Davenport, who'd been a pimp in the '20s, and Freddie Green, and friends from all sorts of aspects of Billie's life, and she interviewed them, tape-recorded the interviews, transcribed the tapes, and worked on the book, more or less, for 10 years.
NPR: 'With Billie': A Jazz Great, As Others Saw Her