►The publisher Arcadia (Charleston, S.C.) has an excellent series of well illustrated short books on the history of almost any NYC neighborhood, as well as on some New York ethnic groups and institutions etc (e.g. Chinese community).
To find some of these books in the BobCat catalog, use the following search pattern:
►ADVANCED SEARCH Arcadia [Any Field] ] And New York [set Any Field to In Subject]
All Historical Societies also have libraries, and some documents and photos are in freely available online collections.