@article{PismaZhETF.21.543,
    title = {Three-pulse phonon (electroacoustic) echo with large relaxation time},
    author = {Popov, S. N. and Krainik, N. N. and Smolenskii, G. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {21},
    issue = {9},
    pages = {543},
    year = {1975},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_22481.shtml},
}