Comment on "Quantum diffusion of 3-He impurities in solid 4- He"
  In this comment I show that the experimental data on quantum diffusion of 3-He impurities in solid 4-He can be explained using the adopted quasiparticle theory. The contention by E.G. Kisvarsanyi and N.S. Sullivan (KS) in Phys.Rev.B v. 48, 16557 (1993) as well as in their Reply (ibid. v. 55, 3989 (1997)) to the Grigor'ev's Comment (Phys.Rev. B v. 55, 3987 (1997)) that "Pushkarov's theory of phonon scattering fails to fit the data by very large factors" is groundless and may result from their bad arithmetical error. This means that the phonon-impurity scattering mechanism of diffusion is consistent with experiment and its neglecting by KS makes their results questionable. 
Dimitar I. Pushkarov