Hardcover By Jerry West Illustrated by Helen S. Hamilton The Happy Hollisters and the Old Clipper Ship The Happy Hollisters and the Merry-Go-Round Mystery The Happy Hollisters at Pony Hill Farm The Happy Hollisters and the Haunted House Mystery The Happy Hollisters and the Mystery at Missile Town The Happy Hollisters and the Whistle-Pig Mystery (front dust jacket has been taped a bit)