Lovecraft mentions Warren in two other short stories. In The Silver Key, which he wrote in 1926, he describes Harley Warren as a man in the south, who was shunned and feared for the blaspemous [sic] things he read in prehistoric books and clay tablets smuggled from India and Arabia. The story's sequel, Through the Gates of the Silver Key, presents Warren as an expert linguist who has mastered the primal Naacal language of the Himalayas. Lovecraft cowrote this latter work with E. Hoffmann Price; they collaborated on the piece from October 1932 to April 1933.