Main experimental papers and reviews - Low-temperature properties of glasses
The universality is remarkable, but yet to be described beyond phenomenological standard model of tunneling two-level systems.
exclusively? thermal conductivity is due to PHONONS!!! Zaitlin-Anderson
1971 Anomalous Low-temperature Thermal Properties of Glasses and Spin Glasses By P. w. ANDERSON, B. I. HALPERIN and c. M. VARMA
1987 Phillips Two-level states in glasses
1971 - Zeller-Pohl
TOGETHER linear-T specific heat and $ T^2$-thermal conductivity Stephens
Freeman- Anderson $150* \lambda = l$
Graebner-1986 Phonon localization in glasses
J. E. Graebner, B. Golding, and L. C. Allen