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

PHONONS IN AMORPHOUS MATERIALS - review - S. Hunklinger