Oh, that is really a long time ago. I just wrote exactly same to another poster who wondered about that name Why Not.
I sat in the tram with that conductor (must have been the 1 or 2). Have never ever been inside the place. But do know there is even a master´s sociology thesis written about how those gay brothels worked by an intruding lady. Had a few of such books but moved home some 2 yrs ago and threw them all away.
In the central public library in AMS, the big still fairly new one east of CS, beyond that Hilton HTL, on some floor is the gay&lesbian (of whatever the new name is this season) documentation centre where they keep about any scientific book about such matters. Cannot lend, but read on the spot.