Invisible Enemy

Övriga publiceringar

1a. The Hydra of Lernea, or The Case of the Gossipers 1946 (Ellery Queen's Mystery Magazine)
1b. The Hydra of Lernea, or The Case of the Gossipers 1946 (Ellery Queen's Mystery Magazine – Ovserseas Edition for the Armed Forces)

2.   The Lernean Hydra 1947 (The Labors of Hercules)

3.   The Lernean Hydra 1984 (Hercule Poirot's Casebook)