| # | Title | Copyright |
|---|---|---|
| 1. | Sign of the Spiral | |
| 2. | The Telltale Scar | 1947 |
| 3. | The Clue of the Cypress Stump | 1948 |
| 4. | The Secret of the Lost Mesa | 1949 |
| 5. | The Hidden Stone Mystery | 1950 |
| 6. | The Secret of Thunder Mountain | 1952 |
| 7. | The Inca Luck Piece | 1955 |
| 8. | Mystery of the Timber Giant |
| A description of the first three books from the back of the dust jacket. |
| A description of the first six books from the inside of a later dust jacket. |