The New York Public Library’s erotica collection (begun in the late 1970's) includes seedy Times Square ephemera, early transgender magazines and copies of Playboy.
Since it does not mention gay I assume it may not be included. (Perhaps that's in the LGBT collection?) Either way this collection is a great way to see what people were looking for in erotica back then (and later) as opposed to how it was later interpreted.
Wednesday 06 January 2016. Updated 01 Feb, 13:00 by Nigel, aka SubDirectory (3)