4239 Coolidge Avenue
This differs from my previous examples in that the initials “J.S.” are closely spaced. Perhaps Mattos had two stamps.
51st Avenue at E. 10th Street
There are several of these marks in the neighborhood. Salvatore DeGuarda is surely the S. DeGuarda whose 1938 mark I’ve documented, and not the same person as Leonard DeGuarda. I will guess, for now, that Salvatore was Leonard’s father.
2139 107th Avenue
This block has several marks from Massaro, whose solo marks (from after his stint as part of Triberti & Massaro, in the 1940s) are rare and always undated. This is the best of the bunch, and probably the best in the city.
10700 block Sunnyside Street
There are three of these big ol’ marks on this short block. Rose may be Manuel Rose, of 38th Avenue.