Safonova, Y.A. и др. 2019. Prevalence of vitamin D deficiency in elderly people with sarcopenia in the north-west of Russia. Вестник Санкт-Петербургского университета. Медицина. 14, 1 (июн. 2019), 58–68. DOI:https://doi.org/10.21638/11701/spbu10.2019.107.