The Mystery of the Flaming Footprints (1971) - Front cover of ''The Mystery of the Flaming Footprints''.The Mystery of the Whispering Mummy (1965) - Front cover of ''The Mystery of the Whispering Mummy''.The Mystery of the Coughing Dragon (1970) - Illustration from ''The Mystery of the Coughing Dragon'' by artist Harry Kane.The Mystery of the Talking Skull (1969) - Front cover of ''The Mystery of the Talking Skull''.The Mystery of the Vanishing Treasure (1966) - Front cover of ''The Mystery of the Vanishing Treasure''.The Mystery of the the Fiery Eye (1967) - Illustration for ''The Mystery of the the Fiery Eye'' by artist Harry Kane.The Secret of the Haunted Mirror (1974) - Front cover of ''The Secret of the Haunted Mirror''.The Mystery of the Silver Spider (1967) - Front cover of ''The Mystery of the Silver Spider''.The Secret of the Crooked Cat (1970) - Front cover of ''The Secret of the Crooked Cat''.The Mystery of the Death Trap Mine - Front cover of ''The Mystery of the Death Trap Mine''.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 Shrinking House (1972) - Front cover of ''The Mystery of the Shrinking House''.The Mystery of the Invisible Dog (1975) - Front cover of ''The Mystery of the Invisible Dog''.The Mystery of the Sinister Scarecrow (1979) - Front cover of ''The Mystery of the Sinister Scarecrow''.The Mystery of the the Fiery Eye (1967) - Front cover of ''The Mystery of the the Fiery Eye''.