Pola Negri Info Sought

I am writing a biography on silent film star, Pola Negri. Would anyone have information on Miss Negri that I could possibly use in the book? Are there any folks out there who knew her or possibly, though a long shot, even worked with her in some capacity? I am particularly interested in her supposed ‘affairs’ with Chaplin and Valentino and the 1930s when she left Hollywood to make films in Germany.
Many thanks:
Tony Villecco-author Silent Stars Speak: Interviews With Twelve Cinema Pioneers (McFarland 2001)
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