Other PF Jeffery related links:
Who Killed St John? (Crypt of Cthulhu 1987)
The Princess and the Black Asteroid (Crypt of Cthulhu 1994)
Golden Goddess and Bloody Times (2006)
ETEPSED (Dagon 1989)
THE VISITOR (The 1974 novel by DFL with much in-built commentary by PFJ).
Poppers In The Wine (1 of the 8 (?) DFL/PFJ fiction collaborations, this one first published in 1998).