73 books • 9 series
Book #3: Materials In Your Home
Book #4: Building Materials
Book #5: Materials On The Move
Book #6: Flight
Book #12: Evangelism Old and New
Book #1: Extreme Danger
Book #1: Tower Treasure
Book #1: The Tower Treasure #1
Book #2: The Arctic Patrol Mystery
Book #2: Running on Fumes
Book #100: The Hardy Boys 100: True Thriller
Book #107: Fast Break
Book #44: Castle Fear
Book #3: The Other Continent
Book #4: Tally and the Angel The Sands of Time