Siegfried Flügge, born in 1912, was a prominent German physicist who made significant contributions to theoretical nuclear physics, quantum physics, and astrophysics. He completed his doctorate under Max Born in 1933 and held positions at various universities, including Frankfurt, Leipzig, and Berlin, where he witnessed and contributed to the discovery of nuclear fission. Flügge's career spanned several decades, during which he taught at universities in Königsberg, Göttingen, Marburg, and Freiburg, retiring in 1977. Flügge's most notable work, "Practical Quantum Mechanics," was first published in 1947 as "Rechenmethoden der Quantentheorie" in German. The book aimed to serve both students and experimental scientists by providing practical applications of quantum mechanics to atomic physics problems. The second edition, published in 1971, was expanded to include new approximation methods, relativistic quantum mechanics, and radiation theory. The book is divided into several volumes, with the second volume focusing on more advanced topics such as the Wentzel-Kramers-Brillouin (WKB) approximation, magnetic fields, and the relativistic Dirac equation. The book is known for its comprehensive problem sets, which have been updated and expanded in subsequent editions to include a wide range of practical problems. It also includes a mathematical appendix that collects and derives special functions used throughout the text. The work has been widely recognized and used as a standard reference in physics education and research.Siegfried Flügge, born in 1912, was a prominent German physicist who made significant contributions to theoretical nuclear physics, quantum physics, and astrophysics. He completed his doctorate under Max Born in 1933 and held positions at various universities, including Frankfurt, Leipzig, and Berlin, where he witnessed and contributed to the discovery of nuclear fission. Flügge's career spanned several decades, during which he taught at universities in Königsberg, Göttingen, Marburg, and Freiburg, retiring in 1977. Flügge's most notable work, "Practical Quantum Mechanics," was first published in 1947 as "Rechenmethoden der Quantentheorie" in German. The book aimed to serve both students and experimental scientists by providing practical applications of quantum mechanics to atomic physics problems. The second edition, published in 1971, was expanded to include new approximation methods, relativistic quantum mechanics, and radiation theory. The book is divided into several volumes, with the second volume focusing on more advanced topics such as the Wentzel-Kramers-Brillouin (WKB) approximation, magnetic fields, and the relativistic Dirac equation. The book is known for its comprehensive problem sets, which have been updated and expanded in subsequent editions to include a wide range of practical problems. It also includes a mathematical appendix that collects and derives special functions used throughout the text. The work has been widely recognized and used as a standard reference in physics education and research.