My reference book says that Mitzi and Sissy #N3965 is a reprint of Evelyn Rudie, which was published in 1958. I don't know who Evelyn Rudie was, though she must have been a minor child celebrity. The cover price on Mitzi and Sissy is 49 cents, which means it was published in the very late 60's or early 70's, and the dolls look contemporary, but the clothes are definitely earlier.
Teklady27 sent me a Wikipedia link for Evelyn Rudie- she was the youngest Emmy nominated child star in the 50's, and she's still very active in the theater. The wiki entry has a photo of the original paper doll cover and dolls. Evelyn was blonde, but the dolls are obviously the same poses as the above scans. http://en.wikipedia.org/wiki/Evelyn_Rudie Thanks Teklady27!
Click on images to enlarge, right click to save as jpgs. Print clothes on plain paper, covers on card stock (though this back cover can be printed on plain paper too).