@article{PismaZhETF.41.381,
    title = {Observation of self-focusing of sound},
    author = {Andreev, V. G. and Karabutov, A. A. and Rudenko, O. V. and Sapozhnikov, O. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {41},
    issue = {9},
    pages = {381},
    year = {1985},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_22372.shtml},
}