Creaciones
| ▲Título▼ | △C▼ | ▲Año▼ | ▲V▼ | ▲Concepto▼ |
|---|
| The Windthrope Legacy (junto a Paul Carrick y Drashi Khendup) |   | 2001 | — | Escritor |
| About Monstres |  | 1994 | — | Escritor |
| Alien Races (junto a Keith Herber) | | 1993 | — | Escritor |
| Animals (junto a Marion Anderson, Sandy Petersen, Justin Schmid y Lynn Willis) | | 2006 | — | Escritor |
| Appendix (to "The Compact Trail of Tsathoggua") | | 1997 | — | Escritor |
| Beasts and Monsters ("Call of Cthulhu 5th Edition") (junto a Sandy Petersen y Lynn Willis) | | 1992 | — | Escritor |
| Campbell Country (junto a Paul Carrick, Drashi Khendup y Gary Sumpter) | | 2001 | — | Escritor |
| The Campbell Mythos (junto a Drashi Khendup) | | 2001 | — | Escritor |
| Creatures of Legend & Folklore (junto a Sandy Petersen, Justin Schmid y Lynn Willis) | | 2006 | — | Escritor |
| Creatures of the Mythos ("Ye Booke of Monstres") (junto a Fred Behrendt, John Carnahan, Larry DiTillio et al.) | | 1994 | — | Escritor |
| Creatures of the Mythos ("Call of Cthulhu 5th Edition") (junto a Sandy Petersen y Lynn Willis) | | 1992 | — | Escritor |
| Creatures of the Mythos ("Malleus Monstrorum") (junto a Marion Anderson, Bruce Ballon, Bill Barton et al.) | | 2006 | — | Escritor |
| Creatures of the Mythos ("The Creature Companion") (junto a Shannon Appelcline, Bill Barton, Fred Behrendt et al.) | | 1998 | — | Escritor |
| Cthulhu Mythos Entities in Victorian Britain (junto a David Grilla) | | 2012 | — | Escritor |
| Deities of the Mythos ("Malleus Monstrorum") (junto a Phil Anderson, Marion Anderson, Bruce Ballon et al.) | | 2006 | — | Escritor |
| Deities of the Mythos ("The Creature Companion") (junto a Phil Anderson, Marion Anderson, Shannon Appelcline et al.) | | 1998 | — | Escritor |
| The Dreamlands Bestiary (junto a K.L. Campbell-Robson, Larry DiTillio, Phil Frances et al.) | | 1997 | — | Escritor |
| Foreword ("Malleus Monstrorum") | | 2004 | — | Escritor |
| Introduction (to "Malleus Monstrorum") | | 2006 | — | Escritor |
| Introduction (to "Tales of the Sleepless City") | | 2013 | — | Escritor |
| Introduction (to "The Creature Companion") | | 1998 | — | Escritor |
| Introduction (to "Ye Booke of Monstres II") | | 1995 | — | Escritor |
| Introduction (to "Ye Booke of Monstres") | | 1994 | — | Escritor |
| Jack the Ripper (junto a Kevin Ross) | | 2012 | — | Escritor |
| Massa di Requiem per Shuggay: A History of The Devil’s Opera | | 2013 | — | Escritor |
