The library IS a good starting point.
Repeat after me: library.princeton.edu, library.princeton.edu, library.princeton.edu
No need to Google it.
===
Try searching the catalog for "mental health" and school as a keyword . Because the focus is NYC you can include that in the search. However, while nothing compares to NY, relevant materials from other locations are potentially useful.
What subject heading(s) does it correspond to?
I always look for a recent report by the Congressional Research Service (not really a book, but will show up in the Catalog)