[PW] Help with book title

[Faulkner, David]

Hello all and good Friday,

A customer is trying to remember the name of a children's book she read
in the 60s. She believes it was written in the 40s or 50s. It was about
a girl named Sue and her sister Laura. Their father was the super of the
building in which they lived. They were friends with two immigrant
children, Magda and Anton, whose father was the janitor for the same
building. The children would go on adventures to the Central Park zoo
and other places. There was also a mean lady who lived in the apartment
below that would bang on the ceiling with a broom if they got too noisy.
The book had black and white illustrations with heavy lines. Thanks for
your help!

David
Austin Public Library