Ingrid Bergman autograph, on Broadway Playbill, 1975, only one month stage run!

Ingrid Bergman was a legendary actress. One time only, for a total of about 30 performances, she appeared as the star of a Broadway play, "The Constant Wife" in April, 1975. My father obtained Ingrid Bergman's autograph immediately after one of the limited performances in April, 1975.
 The autograph is clear and crisp in blue ink on the cover of the playbill above her photograph. The playbill is in excellent condition, no tears and all pages. This is a VERY RARE original autograph.