46 books • 5 series
Book #2: Ace G-Man #2
Book #3: Ace G-Man #3
Book #4: Ace G-Man #4
Book #5: Ace G-Man #5
Book #6: Ace G-Man #6
Book #1: The Masked Marksman #1
Book #2: The Masked Marksman #2
Book #1: Operator 5 #1
Book #2: Operator 5 #2
Book #3: Operator 5 #3
Book #4: Operator 5 #4
Book #5: Operator 5 #5
Book #21: Operator 5 #21
Book #22: Operator 5 #22
Book #24: Operator 5 #24
Book #25: Operator 5 #25
Book #26: Operator 5 #26
Book #3: The Spider #3
Book #4: The Spider #4
Book #5: The Spider #5
Book #6: The Spider #6
Book #7: The Spider #7