CHEUNG, H. H., L.-Y. TONG, and W. W. TO. “Second-Tier Non-Invasive Prenatal Screening for Down Syndrome in a Public Obstetric Unit: The First 12 Months”. Hong Kong Journal of Gynaecology, Obstetrics and Midwifery, vol. 22, no. 1, Apr. 2023, doi:10.12809/hkjgom.22.1.02.