@article{PismaZhETF.30.215,
    title = {An observation of second sound in sapphire},
    author = {Danil'chenko, B. A. and Poroshin, V. N. and Sarbei, O. G.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {30},
    issue = {4},
    pages = {215},
    year = {1979},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_20620.shtml},
}