“Evaluation of the Effectiveness of Multi-Frequency Ultrasound Therapy in the Treatment of Lactational Duct Obstruction in Postpartum Women at Da Nang Hospital for Women and Children”. DA NANG JOURNAL OF MEDICINE AND PHARMACY, vol. 2, no. 3, Sept. 2026, pp. 64-73, https://tapchi.ydn.edu.vn/index.php/yduoc/article/view/83.