522 books • 20 series
Book #1: The Bobbsey Twins
Book #2: The Bobbsey Twins in the Country
Book #4: The Bobbsey Twins at School
Book #5: The Bobbsey Twins at Snow Lodge
Book #6: Bobbsey Twins on a Houseboat
Book #1: The Mystery of the Ghost in the Attic
Book #2: The Mystery of the Dinosaur in the Forest
Book #1: Blue Poodle Mystery
Book #1: The Bobbsey Twins of Lakeport
Book #2: The Bobbsey Twins' Adventure in the Country
Book #2: Secret in the Pirate's Cave
Book #2: Adventure in the Country
Book #3: The Secret at the Seashore
Book #4: Mystery at School
Book #5: At Snow Lodge
Book #6: On a Houseboat
Book #7: Mystery at Meadowbrook
Book #5: Mains and Desserts as Well as Sauces
Book #6: The Camp Fire Mystery
Book #8: Mystery of the Laughing Dinosaur
Book #28: Case of the Vanishing Video
Book #1: Bt New #1: The Secret of Jungle Park
Book #2: The Case of the Runaway Money
Book #3: The Clue That Flew Away
Book #4: New Bobbsey Twins #4
Book #5: The Case of the Close Encounter
Book #4: The Missing Pony Mystery