00698naa#a2200169#i#450# EN\\bibl\113388 20260207142513.6 1994-4683 20250913b2025####ek#y0engy0150####ca RU Improvement of breaststroke leg technique based on the development of key areas of flexibility of swimmers 9-11 years old Journal article Moscow National State University of Physical Education, Sports and Health named after P.F. Lesgaft 2025 3 с. Journal article local Плавание без вспомогательных средств. 797.21 Maretsky Sergey Yur'evich uchzapiski.lesgaft.spb.ru