Application of a biomedical hardware-software complex for the study of ultradian rhythms by heart rate variabilityAnastasia Bashkireva, Sergey Chibisov, Tatyana Bashkireva, Alexander Prutzkow and Dmitriy MaksimovBIO Web Conf., 67 (2023) 03009DOI: https://doi.org/10.1051/bioconf/20236703009