An estimation of the word count puts their number at below 33,000: thus, this is a novella by ISFDB standard.
| Date | Publication | Publisher | Type | Page | |
|---|---|---|---|---|---|
| January 1959 |
|
Threshold of Eternity / The War of Two Worlds | Ace Books | Omnibus | 5 |
| September 1970 |
|
The War of Two Worlds | Dennis Dobson | Chapbook | |
| 1974 |
|
The War of Two Worlds | Dennis Dobson | Chapbook |