AUTHOR=Wendt Julia , Weymar Mathias , Blaser Berenike Lisa TITLE=Alleviating premenstrual symptoms with smartphone-based heart rate variability biofeedback training: a pilot study JOURNAL=Frontiers in Digital Health VOLUME=6 YEAR=2024 URL=https://www.frontiersin.org/journals/digital-health/articles/10.3389/fdgth.2024.1337667 DOI=10.3389/fdgth.2024.1337667 ISSN=2673-253X