1. Becker B (1943) Roentgenpraxis 15: 185, quoted by Köhler and Zimmer
2. Burman MS, Sinberg SE (1940) An anomalous talo-calcaneal articulation: double ankle bones. Radiology 34:239
3. Keats TE (1984) An atlas of normal roentgen variants that may simulate disease. 3rd edn. Year Book Medical Publishers, Chicago
4. Köhler A, Zimmer EA (1968) Borderlands of the normal and early pathological in skeletal roentgenology. Third American edition based on 11th German Edition. Translated and edited by Wilk SP. Grune and Stratton, New York London, p 488
5. March HC, London RI (1956) The os sustentaculi. AJR 96:1114