| The Riches of Bunyan: Selected from His Works
John Bunyan | |
| The Riddle and the Ring; or, Won by Nerve
Gordon MacLaren | |
| The Riddle Club at Sunrise Beach
Alice Dale Hardy | |
| The Riddle Club through the holidays
Alice Dale Hardy | |
| The Riddle of the Frozen Flame
Mary E. Hanshew; Thomas W. Hanshew | |
| The Riddle of the Mysterious Light
Mary E. Hanshew; Thomas W. Hanshew | |
| The Riddle of the Night
Thomas W. Hanshew | |
| The Riddle of the Purple Emperor
Mary E. Hanshew; Thomas W. Hanshew | |
| The riddle of the rangeland
Forbes Parkhill | |
| The Riddle of the Rhine: Chemical Strategy in Peace and War
Victor Lefebure |
