The book "The equations of motion of non-holonomic systems and variational principles of mechanics" by Zegzhd C. A. and its co-authors is a deep and fascinating study in the field of mechanics that will be of interest to both students and professional physicists and engineers. This work is not just a textbook, but a real find for anyone who seeks to understand complex mechanical systems and their behavior. The book focuses on non-holonomic systems that differ from classical holon systems in that their movements cannot be described by simple equations that depend only on coordinates and time. Instead, they require more sophisticated approaches and methods, making their study not only challenging, but also extremely fascinating. The authors invite the reader to immerse himself in the world of variational principles of mechanics, which serve as the basis for the analysis and solution of problems associated with such systems. The book will be of particular interest to senior students of physics and mechanics, graduate students and young scientists who want to deepen their knowledge in the field of theoretical mechanics. It can also be useful to practicing engineers and researchers working in areas related to dynamics and motion control. If you are interested in topics such as mechanics, dynamics, variational methods and theoretical physics, then this publication will be a real discovery for you. The topics raised in the book cover a wide range of issues, ranging from the foundations of the theory of non-holonomic systems to modern approaches to their analysis. The authors consider various variational principles that can be applied to solve problems associated with the movement of such systems. This allows the reader not only to get acquainted with the theory, but also to see the practical application of this knowledge in real problems. The book also contains many examples and tasks, making it particularly useful for self-study. The writing style of Zegjd and his colleagues is clear and accessible, which allows even complex concepts to be explained in simple and understandable language. The authors strive to make the material available to a wide audience, which is certainly one of the main advantages of this book. In it you will find not only theoretical calculations, but also practical recommendations that will help you better understand and apply the principles studied. If you are already familiar with other works of Zegjd, such as "Mechanics Theory" or "System Dynamics", then this book will be a great addition to your library. It will not only expand your knowledge, but also deepen your understanding of mechanical systems, which is an important aspect for any researcher in the field. “The equations of motion of non-holonomic systems and the variational principles of mechanics” is not just a book, but a whole world worth diving into. It offers a unique opportunity to look at mechanical systems from a new perspective and discover new horizons in the study of physics. Do not miss the chance to become part of this fascinating journey into the world of mechanics, where every equation and every theorem can reveal to you new secrets of nature.