. 2020 Nov 11;15(11):e0241497. doi: 10.1371/journal.pone.0241497
© 2020 Volkmann et al
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Fig 2. PRISMA 2009 flow diagram.
