The book "Generalized functions, vp. 4. Some applications of harmonic analysis. Equipped with Hilbert spaces", written by eminent mathematicians and. M. Gelfand and N. I. Vilenkin, is a fascinating and deep immersion into the world of functional analysis and theory of generalized functions. This volume, part of an extensive series, is devoted to the application of harmonic analysis and Hilbert spaces, making it an indispensable source of knowledge for students, graduate students, and researchers in mathematics and related disciplines. From the first pages, the reader is immersed in a complex but exciting world of mathematical concepts that, at first glance, may seem abstract, but actually have many practical applications. The authors masterfully explain how generalized functions can be used to solve real-world problems involving signal analysis, image processing, and even quantum mechanics. Each chapter of the book reveals new horizons, showing how theoretical aspects of harmonic analysis can be applied to solve specific problems. This book will be especially interesting for those who already have basic knowledge in the field of higher mathematics and seek to deepen their knowledge in functional analysis. Students of mathematical, physical and engineering majors will find in it a variety of useful materials that will help them better understand complex concepts and methods. It will also be useful to teachers, researchers and practitioners working in the field of function theory, mathematical physics and applied mathematics. The topics covered in the book cover a wide range of issues, such as the properties of generalized functions, their application in various fields of science, as well as in-depth analysis of Hilbert spaces. The authors raise important questions regarding the relationship between mathematics and physics, which makes the book relevant and interesting for readers seeking to understand how abstract mathematical theories can be used to describe real-world phenomena. The writing style of Gelfand and Vilenkin is clear and logical, which allows the reader to easily follow their thoughts and ideas. They use many examples and illustrations, which makes the material more accessible and understandable. The book is filled with deep reflections and original approaches that not only enrich the reader’s knowledge, but also inspire further research. If you are looking for literature that will help you understand complex mathematical concepts and their practical application, then Generalized Functions, Vol. 4" will be a real find for you. This book will not only expand your horizons, but also help you see how mathematics can be used to solve a wide variety of problems. It will become an indispensable assistant in your educational and professional path. In conclusion, “Generalized functions, p. 4. Some applications of harmonic analysis. Equipped with Hilbert spaces" is not just a textbook, but a real treasure trove of knowledge that inspires new discoveries and research. If you want to immerse yourself in the world of mathematical analysis and discover its amazing possibilities, this book must take its rightful place on your shelf.