Rosemary A. Underhill, John M. Beazley, Stuart Campbell
Underhill R A, Beazley J M, Campbell S.
Comparison of Ultrasound Cephalometry, Radiology, and Liquor Studies in Patients with Unknown Confinement Dates
Br Med J 1971; 3 :736
doi:10.1136/bmj.3.5777.736