@article{PismaZhETF.32.461,
    title = {Evidence of dipole spin glass in magnetically dilute dielectric  $CaF_2$:$Er^{3+}$},
    author = {Atsarkin, V. A. and Demidov, V. V. and Khlebnikov, S. Ya.},
    journal = {Письма в ЖЭТФ},
    volume = {32},
    issue = {7},
    pages = {461},
    year = {1980},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_21768.shtml},
}