## theory - 1949 [Kittel](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5481/kittel%2B1949.pdf) 

## 1951 [Klemens](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5482/klemens.pdf)

- **Why? —- Klemens - Thermal conductivity - Transverse for high temperatures, while longitudinal for low temperatures **


## R. Berman 1951 [Solids at Low Temperatures (Experimental) -The Thermal Conductivities of Some Dielectric Solids](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5563/rspa.1951.0146%2B_1_.pdf)

![nn](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5567/klemens%2Bsummary.png 'nn')

## [Birch-Clark 1940](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5566/ajs.238.8.529.pdf) and particularly [theory - Part 2](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5565/ajs.238.9.613.pdf)

## 1987 [Thermal conductivity of amorphous solids above the plateau](https://knowen-production.s3.amazonaws.com/uploads/attachment/file/5564/cahill-plateau-prb87.pdf) David G. Cahill and R. O. Pohl

> we find above —50 K a magnitude and temperature
> dependence which agrees with the model of the minimum
> thermal conductivity proposed by Slack. In the limit of
> high temperatures, this model leads to a phonon mean
> free path equal to the interatomic spacing as first noted in
> glasses by Birch and Clark and by Kittel.