Poltergeist Society of Oxford
From Jenny Everywhere Wiki
At some point prior to their tangle with the “Tenth Lord Grell”, Jenny Cornelius and Laura Drake visited their universe's Oxford and met real poltergeists as they interacted with the Poltergeist Society of Oxford. (PROSE: Birds and Snakes)
Behind the scenes
Asked on Discord if the Poltergeist Society of Oxford was meant to be the historical Oxford Phasmatological Society, Scott Sanford clarified that the reference hadn't been intentional, but agreed that the connection would make sense, with his Poltergeist Society of Oxford being an evolution of the Phasmatological Society in a universe where it lasted into the 1960s instead of disbanding in 1885.