Naturalization records ~1950s NYC

Hi, I'm looking for naturalization records for my grandfather and great-grandfather, who arrived to the US via Ellis Island after WWII. I have an image of a card from the New York, U.S., Index to Petitions for Naturalization filed in New York City, 1792-1989 database showing my great-grandfather was naturalized in June 1952 in NYC. But I'm looking for a more complete set of documents, and hoping it will also include naturalization records for my grandfather, who was about 17 at the time.

Are there sources for this information other than USCIS? Appreciate any help pointing me in the right direction!