Notes
Per the copyright page of Ace Double: "This novel originally appeared in Analog in two parts under the titles Ultima Thule and Pistolero". Pistolero was the intended title, but it was never published. Instead, it was published later as Hatchetman in Impulse, June 1966.
Publications (4)
| Date | Publication | Publisher | Type | Page |
|---|---|---|---|---|
| 1965 | Planetary Agent X / Behold the Stars | Ace Books | Omnibus | 5|2 |
| June 1974 | The Rival Rigelians and Planetary Agent X | Ace Books | Omnibus | 5|2 |
| September 2011 | Planetary Agent X | Gateway / Orion | Novel | |
| August 2017 | Planetary Agent X | Wildside Press | Novel |