The Mystery of the Screaming Clock (1968) - Front cover of ''The Mystery of the Screaming Clock''.The Mystery of the Dead Man's Riddle (1974) - Front cover of ''The Mystery of the Dead Man's Riddle''The Mystery of the Sinister Scarecrow (1979) - Front cover of ''The Mystery of the Sinister Scarecrow''.The Mystery of the Deadly Double (1978) - Front cover of ''The Mystery of the Deadly Double''.The Mystery of the Silver Spider (1967) - Front cover of ''The Mystery of the Silver Spider''.The Mystery of the Magic Circle (1978) - Front cover of ''The Mystery of the Magic Circle''.The Secret of Shark Reef (1979) - Front cover of ''The Secret of Shark Reef''.The Mystery of the Moaning Cave (1968) - Front cover of ''The Mystery of the Moaning Cave''.The Mystery of the Green Ghost (1965) - Front cover of ''The Mystery of the Green Ghost''.The Secret of the Crooked Cat (1970) - Front cover of ''The Secret of the Crooked Cat''.The Secret of Terror Castle (1964) - Front cover of ''The Secret of Terror Castle''.The Secret of Skeleton Island (1966) - Front cover of ''The Secret of Skeleton Island''.The Mystery of the Silver Spider (1967) - Front cover of ''The Mystery of the Silver Spider''.The Mystery of the Monster Mountain (1973) - Front cover of ''The Mystery of the Monster Mountain''.The Mystery of the Coughing Dragon (1970) - Illustration from ''The Mystery of the Coughing Dragon'' by artist Harry Kane.