AMA He X, Liu H. Placenta retention is associated with threatened abortion at the early stage of pregnancy. Journal Obstetrics and Gynecological Investigations. 2023;6(1):1-6. doi:10.5114/jogi.2023.128810. APA He, X., & Liu, (2023). Investigations, 6(1), 1-6. https://doi.org/10.5114/jogi.2023.128810 Chicago Xiaoya, Huishu Liu. 2023. "Placenta pregnancy". Investigations 6 (1): Harvard pp.1-6. ML...