“This new edition has confirmed the important commitment to provide students and researchers with an exhaustive and self-contained presentation of the mathematical foundations of quantum mechanics, enriched by many exercises, often with solution, and an extensive literature. … The spectral theory and a due treatment of unbounded operators still provide the core of the book, which however provides the interested reader with rigorous statements and proofs for all the many different chapters of mathematics relevant to non-relativistic quantum mechanics.” (Bassano Vacchini, zbMATH 1395.81001, 2018)