In the unique book “The Psychology of an Effective Manager. Flexibility. Effective management. Psychology of a manager. Book 1. Management Situation” by Leonard Zawalkiewicz sets out in accessible and interesting language the fundamental principles and methods of management applicable in a wide variety of business situations. After all, very often you have to face the fact that for effective management it is not enough to know a lot and work hard; you need to understand the reasons, principles and meaning of management. The book teaches how to become an effective manager without a special diploma in management and even without innate leadership qualities. After reading the book, you will be convinced that the most difficult thing in management is to understand that managing is simple. The book is intended for the widest range of thoughtful readers: managers, business owners, managers and all those who would like to become an effective manager and understand in the secrets of management. Book “Psychology of an effective manager. Flexibility. Effective management. Psychology of a manager. Book 1. Management Situation" opens a trilogy of books by Leonard Zawalkiewicz, which also includes the books "Subject of Management" and "Management Process".