 "The Missing Heirloom", "The Disappearing Candlesticks", and "The Mystery of the Old Barn" were published in hardcover with dustjackets, illustrated by Margaret Jervis.Whitman changed formats for their juvenile line by the time "The Lending Library" and "The Broadcast Mystery" were published in the mid-1950s.Rather than having illustrated dustjackets over solid-color hardcovers, these two titles have wrap-around, full-color, illustrated covers, covered in cellophane.