The Flying Spy
Camillo De Carlo
Agent Nine Solves His First Case - A Story of the Daring Exploits of the "G" Men
Graham M. Dean
The Secret Victory
Stephen McKenna
Frigid Fracas
Mack Reynolds
Spies of the Kaiser: Plotting the Downfall of England
William Le Queux
Air Service Boys Over the Enemy's Lines; Or The German Spy's Secret
Charles Amory Beach
Final Strike
Robert A. Adamcik
Personal Strike
Robert A. Adamcik
Forbidden Cargoes
Roy J. Snell
The Lone Ranger Rides
Fran Striker
Master of Men
E. Phillips Oppenheim
Royal Slaughter
Rob Pierce
Nautical Strike
Robert A. Adamcik
Gil the Gunner: The Youngest Officer in the East
George Manville Fenn
Treachery in Outer Space
Carey Rockwell
Within The Enemy's Lines
Oliver Optic
The Time Traders
Andre Norton
Triple Spies
Roy J. Snell
The Czar's Spy: The Mystery of a Silent Love
William Le Queux
The Automobile Girls at Washington; Or Checkmating the Plots of Foreign Spies
Laura Dent Crane
Fatal Pursuit
Ava S. King
A Boy from Tangier
D. Groll
North by night
Peter Burchard
Nick Carter rescues a daughter; or The junior partner's strange behavior
Nicholas Carter
The traitor's way
S. Levett Yeats
Watching on the Rhine
Violet R. Markham
Hare Sitting Up
Michael Innes
The Secret Vanguard
Michael Innes
