Kimmich, N., J. Birri, R. Zimmermann, and M. Kreft. “Association Between Levator Ani Muscle Avulsions and Technique of Vacuum Extraction – a Prospective Exploratory Study”. Swiss Medical Weekly, vol. 150, no. 2728, July 2020, p. w20280, doi:10.4414/smw.2020.20280.