1. L. D. Landau and E. M. Lifshitz,Fluid Mechanics(Pergamon, Oxford, 1959), Chap. XVI.
2. I. M. Khalatnikov,An Introduction to the Theory of Superfluidity(Benjamin, New York, 1965), Chap. 13.
3. Second Sound in Liquid Helium II
4. G. B. Whitham,Linear and Nonlinear Waves(Wiley, New York, 1974), Chaps. 2 and 8.
5. Chapter II Application of Quantum Mechanics to Liquid Helium