00464naa#a2200169#i#450# EN\INFRA-M\bibl\6185 20260206171800.5 1998-0728 20150617b2015####ek#y0engy0150####ca RUS RU Problem Situations at Primary School Lesson Journal article Moscow INFRA-M Academic Publishing LLC. 2015 3 с. Journal article local Varanitsa L. zh-szf.ru