Adaptation of students to distance learning in COVID-19 conditions in terms of ultradian rhythms of the cardiovascular systemTatyana Bashkireva, Anastasia Bashkireva, Alexander Morozov, Alexander Severin, Nadezhda Fateeva, Larisa Baykova and Evgeniya SeverinaE3S Web Conf., 211 (2020) 04010DOI: https://doi.org/10.1051/e3sconf/202021104010