Frank Knight, (Rodale Press, 1991), ISBN 0-87857-965-6* "Cheetah", Katherine (or Kathrine) & Karl Ammann, Arco Pub, (1985), ISBN 0-668-06259-2.
Frank Knight, (Rodale Press, 1991), ISBN 0-87857-965-6* "Cheetah", Katherine (or Kathrine) & Karl Ammann, Arco Pub, (1985), ISBN 0-668-06259-2.