KWAN, W. S., S.- wing CHAN, and W.- hon LI. “The Birth Ball Experience: Outcome Evaluation of the Intrapartum Use of Birth Ball”. Hong Kong Journal of Gynaecology, Obstetrics and Midwifery, vol. 11, no. 1, Mar. 2023, doi:10.12809/hkjgom.11.1.114.