1. Gorlin RJ (1990) Syndromes of the head and neck, third edition. Oxford University Press, New York, p 143
2. Burn J (1986) Williams syndrome. J Med Genet 23: 389
3. Kaplan P, Kirschner M, Watters G, Costa MT (1989) Contractures in patients with Williams syndrome. Pediatrics 84: 895
4. Morrissy RT (ed) (1990) Pediatric orthopaedics, third edition. Lippincott, Philadelphia, p 574
5. Tachdjiam MO (1990) Pediatric orthopedics, 2. edn. Saunders, Philadelphia, p 180