Acceptability of a dapivirine levonorgestrel vaginal ring in two Phase 1 trials (MTN-030/IPM 041 and MTN-044/IPM 053/CCN019): Implications for multipurpose prevention technology development - Barbara A. Friedland; Holly Gundacker; Sharon L. Achilles; Beatrice A. Chen; Craig Hoesley; Barbra A. Richardson; Clifton W. Kelly; Jeanna Piper; Sherri Johnson; Brid Devlin; John Steytler; Kyle Kleinbeck; et al. (PLoS ONE)