The Mystery of the Dancing Devil (1976) - Front cover of ''The Mystery of the Dancing Devil''.The Mystery of the Moaning Cave (1968) - Front cover of ''The Mystery of the Moaning Cave''.The Secret of the Haunted Mirror (1974) - Front cover of ''The Secret of the Haunted Mirror''.The Mystery of the Green Ghost (1965) - Front cover of ''The Mystery of the Green Ghost''.The Mystery of the Dancing Devil (1976) - Front cover of ''The Mystery of the Dancing Devil''.The Secret of the Phantom Lake (1973) - Front cover of ''The Secret of the Phantom Lake''.The Mystery of the Flaming Footprints (1971) - Illustration for the Danish release of ''The Mystery of the Flaming Footprints'' by artist Peter Madsen.The Mystery of the Flaming Footprints (1971) - Front cover of ''The Mystery of the Flaming Footprints''.The Mystery of the Monster Mountain (1973) - Front cover of ''The Mystery of the Monster Mountain''.The Secret of the Crooked Cat (1970) - Front cover of ''The Secret of the Crooked Cat''.The Mystery of the Vanishing Treasure (1966) - Front cover of ''The Mystery of the Vanishing Treasure''.The Mystery of the Talking Skull (1969) - Front cover of ''The Mystery of the Talking Skull''.The Mystery of the Dead Man's Riddle (1974) - Front cover of ''The Mystery of the Dead Man's Riddle''The Mystery of the Stuttering Parrot (1964) - Front cover of ''The Mystery of the Stuttering Parrot''.The Mystery of the Headless Horse (1977) - Front cover of ''The Mystery of the Headless Horse''.