Pavlov, I. P. Twenty Years of Objective Study of the Higher Nervous Activity (Behavior) of Animals. Conditioned Reflexes (Dvadtsatiletniy opyt...), 1951. In Russian.

Павлов И. П.
Двадцатилетний опыт объективного изучения высшей нервной деятельности (поведения) животных. Условные рефлексы. / Сборник статей, докладов, лекций и речей. Издание 7-е с приложением. Художник С. М. Мельцер.
Москва : Медгиз (Государственное издательство медицинской литературы), 1951.
508 с. : ил. ; Увеличенный формат. Твердый издательский переплет. Тираж 30 000 экз.
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Pavlov, Ivan.
Twenty Years of Objective Study of the Higher Nervous Activity (Behavior) of Animals. Conditioned Reflexes. / A collection of articles, reports, lectures, and speeches. 7th edition with supplement. Artist S. M. Meltser.
Moscow : Medgiz (State Publishing House of Medical Literature), 1951.
508 pp. : ill. ; Enlarged format. Hardcover. Edition of 3,000 copies. In Russian.

This 1951 volume is a definitive 7th edition of Ivan Pavlov’s seminal work, a book that fundamentally shifted the landscape of world science by establishing the objective study of behavior. Compiled as a comprehensive collection of Pavlov's articles, reports, and lectures, it chronicles the evolution of his thought over two decades of rigorous experimentation. The text provides a deep dive into the internal logic of the brain's regulatory functions, including the arrangement of conditioned reflexes as the primary mechanism for an organism's adaptation to its environment. This specific edition is enhanced by a significant supplement containing two vital articles: "New Research on Conditioned Reflexes" and "The Problem of Sleep," which further explore the complex inhibitory and excitatory processes governing the higher nervous system.
Published by Medgiz during a period of intense focus on Pavlovian doctrine in the Soviet Union, the book stands as a monument to scientific materialism. The 508-page text is accompanied by detailed illustrations and technical drawings that visualize his laboratory methods and neurological findings. The volume was designed by artist S. M. Meltser, featuring a solid, enlarged hardcover format that reflects its importance as a foundational textbook for generations of doctors, biologists, and psychologists. Despite a print run of 30,000 copies, this mid-century medical imprint remains a highly sought-after primary source for bibliophiles and historians of science, documenting the precise moment when the subjective "soul" was replaced by the objective study of the higher nervous activity in the annals of Russian medicine.