Special Preface -- Editor’s Foreword -- Vita -- Preface -- Translator’s Preface -- Elementary Excitations -- The Energy Spectrum of a Quantum Liquid and Superfluidity 1 , 2 , 3 -- The Thermodynamic Functions of Helium II -- The Quantization of the Motion of the Liquid -- The Relation Between the Excitation Spectrum and the Structure Factor of Liquid Helium II -- The Energy Spectrum of a Weakly Nonideal Bose gas -- On the form of the Elementary Excitation Spectrum in the Vicinity of Singular Points 9 -- Interactions Between Elementary Excitations 10 , 11 -- Hydrodynamics -- The Hydrodynamics of Superfluids 12 -- The Dissipative Terms in the Hydrodynamic Equations 13 -- The Propagation of Sound in a Superfluid -- The Excitation of Sound Waves in a Superfluid 14 , 15 -- The Absorption of Sound 16 -- Discontinuities in a Superfluid 17 -- Fourth Sound 18 -- Capillary Waves -- The Hydrodynamics of a Rotating Superfluid 19 -- Superfluid Hydrodynamics Near the λ-Point 22 -- Kinetic Phenomena -- The Kinetic Equation for Elementary Excitations 13 -- Thermal Conductivity -- The First Viscosity -- The Coefficients of Second Viscosity of Helium II -- Sound In Helium II Near Zero Temperature -- Heat Exchange Between a Solid and Helium II -- Impurities in Helium II -- Solutions of Impurities in Helium II -- The Diffusion Coefficient and Thermal Conductivity in Weak Solutions of HE3 in Helium II31 -- Reprints -- The Theory of Superfluidity of Helium II -- Letters to the Editor on the Theory of Superfluidity of Helium II