First and second trimester antenatal screening for Down's syndrome: the results of the Serum, Urine and Ultrasound Screening Study (SURUSS) - Wald, N J; Rodeck, C; Hackshaw, A K; Walters, J; Chitty, L; Mackinson, A M (Health Technol Assess, 2003)
. Doi: 10.3310/hta7110