Hi again, Horst,
Just found this- but I must go to bed! Kirk Collection: Popular Song Index (Commercial Sheet Music) Part 6: 1923-1929 which lists:
Title: You're a real sweetheart.
First Line: It's mighty hard to find a sweetheart, someone who's different from the rest
Chorus: When my pals turned me down you're the pal I found, you're a real sweetheart
Music by: Friend, Cliff.
Words by: Caesar, Irving.
P/P/D: New York : Leo. Feist Inc., c1928.
Location: SPC, KIRK SHEET 1923-1929

There is a link on that page for photocopy requests for the sheet music. Let us know how you get on!

Noreen