This book presents a novel treatment of some unusual topics of non-relativistic theory of quantum mechanics, not often covered in classic texts. Notable among these are the first quantized theory of photons and neutrons (most books give the second quantized theory); Bohr–Sommerfeld ‘action’ as differential operators with their eigenvalues n and l and their corresponding eigenfunctions; parabose and parafermi symmetries of identical particles; Dirac’s initiation of Lagrangian formulation of quantum mechanics (also known as transformation theory) and its elaboration and completion by Feynman; topological phase of the wavefunction in Bohm–Aharonov, Aharonov–Casher and neutron interferometer experiments (examples of the Berry phase); and quantum beats such as Stark and exchange oscillations similar to ‾Κ Κ0 and neutrino oscillations in particle physics. Graduate students of physics will find this fresh exposition of topics interesting as also will teachers of physics. The book is intended to broaden one's understanding of quantum mechanics. This is a reference book that most physics departments at universities would like to procure.