Finding rights that aren't on Doollee - any ideas?

I'm trying to work out who holds the rights to "The 25th Annual Putnam County Spelling Bee", with a tentative view to proposing it for UDS to put on at some point next year - mostly for selfish reasons, as I'm currently quite in love with it! I can't find anything Googling, it's not on the musical's official website or HalLeonard, and Doollee doesn't list any literary agent. Are there other websites I could try? Otherwise I can always call Sydney Theatre Company... but any other ideas would be much appreciated! Cheers! :)