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