Group Analysis of Differential Equations by L. In. Ovsyannikova is a fascinating and deep dive into the world of mathematical theory, which finds application in a wide variety of fields of science and technology. This work will be a real find for students, graduate students and teachers, as well as for anyone interested in mathematics and its practical aspects. On the pages of the book, the author offers readers a unique look at group analysis, which is a powerful tool for solving differential equations. Ovsyannikov not only describes the theoretical foundations, but also demonstrates how this knowledge can be applied in practice. It considers various methods and approaches that allow us to find the symmetry of equations, which in turn facilitates their solution. The reader will be able to see how abstract mathematical concepts can be used to solve real-world problems, making the material particularly valuable to practitioners. The book will be interesting not only for those who are already familiar with differential equations, but also for those who are just starting their way in this area. L. In. Ovsyannikov masterfully explains complex ideas, making them available to a wide audience His style of presentation is clear and logical, which allows the reader to easily absorb the material. Each chapter of the book contains many examples and tasks that help to consolidate the knowledge gained and develop the skills of applying the theory in practice. The topics raised in the book cover a wide range of issues, ranging from the basic concepts of group analysis to more complex aspects, such as the application of symmetries to partial-derivative equations. Ovsyannikov also pays attention to modern achievements in this area, which makes the book relevant and useful for researchers and practitioners. Readers will be able to learn about the latest methods and approaches used in scientific research and engineering practice. The book "Group analysis of differential equations" will be an indispensable tool for those who want to deepen their knowledge in the field of mathematics. It will be useful both for students studying mathematics, physics or engineering disciplines, and for professionals working in scientific and research institutions. If you are interested in topics such as mathematical physics, theoretical mechanics or applied mathematics, this book should definitely take a worthy place in your library. L. In. Ovsyannikov is an author with extensive experience in mathematics and its applications. His works are distinguished by a high level of scientific rigor and practical orientation .. Among his other well-known works are works on the theory of differential equations and mathematical physics, which have also received recognition in the scientific community. Ovsyannikov's style combines a deep understanding of the subject and the ability to convey complex ideas to the reader, which makes his books in demand and relevant. If you are looking for literature that will help you understand the intricacies of group analysis and its application to differential equations, "Group Analysis of Differential Equations" L. In. This is exactly what you need. This book will not only enrich your knowledge, but also inspire new research and discoveries in the fascinating world of mathematics.