I need your help.

I have started doing research for a book on films which have open endings or fail to clearly answer a major question elicited by the plot. Consequently, these films deny the viewer narrative closure. Some examples of what I have in mind...You know how by the end of L'avventura we still don't know what happened to the socialite who got lost island-hopping and became the subject of a search, and how there's no way of knowing if the man and the woman actually met Last Year at Marienbad, and whether or not Vero ran over the boy found dead on the side of the road in The Headless Woman? This type of narrative characteristic can be found, to varying degrees, in the works of these directors: Hitchcock (Suspicion,Vertigo, Psycho, The Birds), Antonioni, Resnais, Haneke (as of late), Kiarostami, Lynch, Duras, and a few others.

Please share your thoughts and/or nominate any films you can think of that "fit the bill". Thanks!
*If you cannot post, e-mail me at o.jubis@miami.edu