Strelkov, S. P. Introduction to the Theory of Oscillations (Vvedenie v teoriyu kolebaniy), 1964. In Russian.

Стрелков С. П. Введение в теорию колебаний. / Учебник для физических факультетов государственных университетов. 2-е издание, переработанное.
Москва : Наука. Главная редакция физико-математической литературы, 1964.
437 с. : черт. Твердый издательский переплет, обычный формат (22 см).
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Strelkov, S. P. Introduction to the Theory of Oscillations (Vvedenie v teoriyu kolebaniy). / Textbook for physics faculties of state universities. 2nd edition, revised.
Moscow : Nauka. Main Editorial Board of Physico-Mathematical Literature, 1964.
437 pp. : fig. Hardcover, standard format (22 cm). In Russian.

This 1964 revised edition by Sergey Strelkov is a classic of Soviet pedagogical literature in the field of physics. Based on the author's extensive lecture courses at the Moscow State University (MSU), this textbook became the gold standard for students of physics and engineering across the USSR. While many contemporary texts focused heavily on either pure mechanics or radio engineering, Strelkov’s "Introduction" was celebrated for its unified approach, treating mechanical and electromagnetic oscillations through a single physical and mathematical lens.
The second edition, published by the prestigious "Nauka" house, was significantly updated to include modern developments in nonlinear oscillations and the theory of automatic control. The text meticulously covers free and forced oscillations, resonance phenomena, systems with multiple degrees of freedom, and the stability of motion. Strelkov was particularly adept at explaining the phase plane method, which remains a cornerstone of the qualitative theory of differential equations.
The book is characterized by its rigorous yet accessible mathematical apparatus, utilizing linear and nonlinear differential equations to describe real-world physical systems. It is filled with precise technical drawings and diagrams that illustrate complex wave interactions and self-oscillating systems.
For physicists, historians of science, and collectors of Soviet academic literature, this 1964 edition represents the "Golden Age" of Soviet theoretical physics education. Its durability as a reference tool is such that it continues to be cited in modern research on acoustics, radio physics, and structural mechanics.