Recently, I've been reading Strangers: Homosexual Love in the Nineteenth Century by Graham Robb because I wanted something more in depth and dedicated than shorter articles might provide. It doesn't cover much beyond parts of Europe and some of America, with an emphasis on the more well-to-do, but that's due primarily to the lack of good records for those sections of society to validate any of his research and others.
But let me say this. It is utterly fascinating. The tone is a tad dry, so it's not really fast reading at all, but the information it imparts casts new light on the period for me. Once you get past the beginning, which focuses on statistical analysis of crimes and punishments, you get more anecdotes that help bring it all to life. If you're not familiar with gay history, the constant barrage of names might be a little overwhelming at first, but honestly, for me, it just compelled me to do more research into those I didn't recognize.
At the end of the day, I highly recommend this to anyone with an interest in gay history and who is comfortable with prose that doesn't talk down to the reader. I imagine it's going to be a great resource for me in years to come. My only regret is that I didn't read it sooner.