1. F. B. Silsbee,Bull. Nat. Bur. Std. 14, 301 (1918).
2. A. B. Pippard,Phil. Mag. 41, 243 (1950).
3. T. M. Lifshitz,Zh. Eksp. Teor. Fiz. 20, 834 (1950).
4. W. H. Cherry and J.I. Gittleman, Office of Naval Research Symposium ReportACR-50, 75 (1960).
5. F. London,Superfluids, Vol. 1 (Wiley, New York, 1961, Chaps. XV-XX).