Army of the Fantastic
John Marco & John Helfers
Future Crimes
Martin H. Greenberg & John Helfers
Man vs. Machine
Space Stations
Stronger Than Fate
John Helfers
The Valdemar Companion
John Helfers & Denise Little
Valdemar (1)
The Vorkosigan Companion
Lillian Stewart Carl & John Helfers
Vorkosi-verse (1)