Helen S. Hamilton

The Happy Hollisters at Sea Gull Beach

The Happy Hollisters and the Trading Post Mystery

The Happy Hollisters and the Ghost Horse Mystery

The Happy Hollisters at Circus Island

The Happy Hollisters on a River Trip

The Happy Hollisters at Pony Hill Farm

The Happy Hollisters and the Scarecrow Mystery

The Happy Hollisters and the Monster Mystery

The Happy Hollisters and the Secret Fort

The Happy Hollisters at Snowflake Camp

The Happy Hollisters and the Sea Turtle Mystery

The Happy Hollisters and the Secret Fort

The Happy Hollisters and the Cuckoo Clock Mystery

The Happy Hollisters and the Ice Carnival Mystery

The Happy Hollisters and the Mystery in Skyscraper City

The Happy Hollisters and the Mystery of the Totem Faces

The Happy Hollisters and the Merry Go 'Round Mystery

The Happy Hollisters and the Swiss Echo Mystery

The Happy Hollisters at Mystery Mountain

The Happy Hollisters and the Secret of the Lucky Coins