55 books
The Motor Rangers on Blue Water; or, The Secret of the Derelict
The Boy Aviators in Nicaragua; or, In League with the Insurgents
The Boy Aviators on Secret Service; Or, Working with Wireless
The Border Boys with the Mexican Rangers
The Boy Scouts and the Army Airship
The Ocean Wireless Boys On The Pacific
The Ocean Wireless Boys On War Swept Seas
The Motor Rangers' Wireless Station
The Dreadnought Boys On Aero Service
The Dreadnought Boys Aboard A Destroyer
The Dreadnought Boys On A Submarine
The Boy Aviators With The Air Raiders
The Border Boys In The Canadian Rockies
The Border Boys With The Texas Rangers
The Border Boys Along the St. Lawrence
The Boy Aviators In Nicaragua
The Dreadnought Boys on Battle
The Bungalow Boys North Of Fifty-Three
The Boy Scouts at the Canadian Border
The Border Boys on the Trail
The Motor Rangers Through the Sierras
The Bungalow Boys in the Great Northwest
The Bungalow Boys Along the Yukon
The Boy Aviators in Record Flight