LOS ANGELES, California (CNN) -- Photographer Larry Birkhead, who was proved in April to be the biological father of former Playboy playmate Anna Nicole Smith's daughter, said Tuesday he will sue the author and publisher of a new book on Smith's death that contains allegations he called "pure fiction." Larry Birkhead questions the reliability of sources used in a new book about Anna Nicole Smith. "I've instructed my attorney to sue Rita Cosby, the publisher and any source that spits out some of that false, defamatory information that's in there," Birkhead said Tuesday on CNN's "Larry King Live." "If I were Rita Cosby, I'd be very concerned."Book alleges Larry Birkhead, Howard K. Stern had affair"That's totally false and it's defamatory," Birkhead saysStern was Smith's boyfriend at time of her death; Birkhead fathered her child
_ and Birkhead, she said, were previously engaged in a legal struggle against each other and appeared to be enemies, but "now they're friends ... and it begs the question why.