I recommend Requirements Engineering: Fundamentals, Principles, and Techniques by Klaus Pohl. The book provides a comprehensive, well-structured, and modern introduction to the foundations, principles, and techniques of Requirements Engineering. It presents a coherent conceptual framework, explains core activities such as elicitation, documentation, and negotiation in a clear and systematic manner, and illustrates all aspects with numerous examples.
Klaus Pohl is one of the leading experts in the field, and his extensive experience is visible on every page. The book combines theoretical soundness with practical applicability, making it valuable both for understanding the discipline and for supporting its application in real projects.
Thanks to its clear structure, didactic quality, and the depth with which key concepts are presented, it serves as an excellent resource for professionals, students, and lecturers alike.