Condition: Almost all books have a name/short message inscribed on the inside cover page (examples in photos). Other than that and a few other cosmetic flaws these books are in great shape! The only duplicate is the muster of cabin island (1966) Years: 1959 - The Tower Treasure and The House On The Cliff 1962 - The Secret Of The Old Mill and The Mussing Chums 1963 - Hunting for Hidden Gold 1964 - The Secret Of The Caves 1965 - The Great Airport Mystery 1966 - The Mystery Of Cabin Island (2x) 1967 - What Happened At Midnight 1989 (printing) - A Figure In Hiding