This is a used set of The New Bobbsey Twins Books. Included is books number 4, 9, & 12.  by Laura Lee Hope. These are used paperback books. Book # 4, The Secret in the Sand Castle, has creases and a tear in the front cover. Book # 9, The Clue in the Classroom is in used condition with some wear along the edges of the covers. Book # 12, The Secret of the Sunken Treasure, is also in used condition with some wear along the edges of the covers. Each book has the initials of the previous owner on the inside cover.