1. VLI Corporation: (VCS) Instruction Booklet. Irvine, CA.
2.
2. Hailer JO, Shkolnik A, Fellows RA: Clinics in Diagnostic Ultrasound: Ultrasound in Pediatrics. New York, Churchill Livingstone, 1981, p 180-180.
3.
3. Sanders RC, James AE, Fleischer AC, et al: The Principles and Practice of Ultrasonography in Obstetrics and Gynecology, ed 2. New York, Appleton-Century-Crofts, 1980, p 404-404.
4.
4. Pritchard JA, MacDonald PC: Williams Obstetrics, ed 16. New York, Appleton-Century-Crofts, 1980, pp 1028-1029.