What is the author's style in Diane Arbus: A Biography by Patricia Bosworth?

Author Patricia Bosworth was not an intimate friend of Diane Arbus, although she was employed as a fashion model on three occasions. As she states in the preface to her work, she ran into Diane on several occasions and had some conversations with her. Bosworth admits that the information obtained for this biography came from many others who knew Diane intimately, including relatives, friends, and business associates, but not from Diane's children, former husband, or Marvin Israel, who perhaps had the most significant impact on Diane's adult life after her separation from husband Allan.