Copeland published a brochure entitled "The Zanthu Tablets: A Conjectural Translation" in 1916. He made the rough translation using a key borrowed from the estate of Colonel Churchward, the last qualified translator of ancient Naacal, and heavily edited it out of a concern for "public sanity". The controversial brochure was later denounced by the academic community and was suppressed by the authorities. Copeland's later manuscripts were never published. Ten years after the publication of the brochure, Copeland died in an asylum.