00507naa#a2200169#i#450# EN\INFRA-M\bibl\6712 20240720171656.6 1998-0701 20131017b2013####ek#y0engy0150####ca RUS RU Profitability marginal profit in the system marginal analysis of the economic subject Journal article Moscow INFRA-M Academic Publishing LLC. 2013 3 с. Journal article local Smirnova Yu. naukaru.ru