Prominent seasonality of 25(OH)D vitamin deficiency in Latvia: Age and gender-related variations and testing regimenSergey Nikulshin, Jana Osite, Stella Lapina, Anda Krisane, Iveta Dzivite-Krisane and Dace GardovskaSHS Web Conf., 131 (2022) 02004DOI: https://doi.org/10.1051/shsconf/202213102004