The Mystery of the Coughing Dragon (1970) - Front cover of ''The Mystery of the Coughing Dragon''.The Mystery of the Magic Circle (1978) - Front cover of ''The Mystery of the Magic Circle''.The Mystery of the Silver Spider (1967) - Front cover of ''The Mystery of the Silver Spider''.The Mystery of the Deadly Double (1978) - Front cover of ''The Mystery of the Deadly Double''.The Mystery of the Screaming Clock (1968) - Front cover of ''The Mystery of the Screaming Clock''.The Mystery of the Invisible Dog (1975) - Front cover of ''The Mystery of the Invisible Dog''.The Secret of Terror Castle (1964) - Front cover of ''The Secret of Terror Castle''.The Mystery of the Death Trap Mine - Front cover of ''The Mystery of the Death Trap Mine''.The Secret of the Haunted Mirror (1974) - Front cover of ''The Secret of the Haunted Mirror''.The Secret of the Phantom Lake (1973) - Front cover of ''The Secret of the Phantom Lake''.The Mystery of the Singing Serpent (1972) - Front cover of ''The Mystery of the Singing Serpent''.The Mystery of the Nervous Lion (1971) - Front cover of ''The Mystery of the Nervous Lion''.The Mystery of the Dead Man's Riddle (1974) - Front cover of ''The Mystery of the Dead Man's Riddle''The Mystery of the Magic Circle (1978) - Front cover of ''The Mystery of the Magic Circle''.The Mystery of the Dancing Devil (1976) - Front cover of ''The Mystery of the Dancing Devil''.