1. L.D. Landau and E.M. Liftshits, Chap. 21 in Theory of Elasticity, Pergamon Press 1970.
2. H.J. Jensen, Y. Brechet, A. Brass, J. Low Temp. Phys. 74, 293 (1989).
3. W. F. Vinen in Superconductivity,Vol. II, ed. R. D. Parks (Marcel Dekker, New York, 1969)
4. See also Y. B. Kim and M. J. Stephen, ibidem.
5. H. J. Jensen, A. Brass and A. J. Berlinsky, Phys. Rev. Lett. 60, 1676 (1988).