Korovkin, Pavel. The Definite Integral and Series (Opredelennyi integral i ryady). First edition, 1959. In Russian.

Коровкин, Павел Петрович. Определенный интеграл и ряды : учебное пособие для педагогических институтов.
Москва : Государственное учебно-педагогическое издательство Министерства просвещения РСФСР (Учпедгиз), 1959. 176 страниц ; немного увеличенный формат.
Твердый издательский переплет. Тираж 14 000 экземпляров.
Переплет хороший: потертость корешка и углов. Блок очень хороший: бумага чистая, шитье крепкое, текст полный.
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Korovkin, Pavel Petrovich (1913-1985). The Definite Integral and Series : a textbook for pedagogical institutes.
Moscow : State Educational-Pedagogical Publishing House of the Ministry of Education of the RSFSR (Uchpedgiz), 1959. 176 pp., with illustrations ; slightly increased format.
Hardcover. Print run of 14,000 copies.
Binding good: wear to the spine and corners. Text block very good: paper clean, sewing firm, text complete throughout.

The first edition of a calculus textbook by one of Soviet mathematics' most internationally cited figures in a field far removed from the didactic modesty of this small volume. Pavel Petrovich Korovkin was born in 1913 in Vesyegonsk to a peasant family and, from age one, was raised in the town's orphanage where his mother worked as a laundress. He went on to graduate from Leningrad University's mechanics-mathematics faculty in 1936, defended a doctoral dissertation in 1947 on the convergence of polynomial series and orthogonal polynomials, and became a professor in 1948, eventually chairing the mathematics department at the Moscow Automobile and Road Construction Institute. Korovkin is remembered worldwide for a 1953 theorem, now universally known as Korovkin's theorem, which shows that the convergence of a sequence of positive linear operators to the identity can be verified by testing it on just three simple functions rather than the entire space; the result founded what is still an active branch of approximation theory known as Korovkin-type approximation theory, with dedicated conferences and monographs continuing into the twenty-first century. This textbook on definite integrals and series, prepared for students at pedagogical institutes training to become school and college mathematics teachers, was among Korovkin's principal didactic works alongside his two-volume university course in mathematical analysis and his widely translated book Inequalities. It offers a window into the everyday teaching career of a mathematician whose research name would go on to circulate far beyond the Soviet Union, in functional analysis literature worldwide.