@article{PismaZhETF.48.109,
    title = {Experimental observation of two-dimensional focusing of x rays in backscattering},
    author = {Kushnir, V. I. and Suvorov, E. V.},
    journal = {Письма в ЖЭТФ},
    volume = {48},
    issue = {2},
    pages = {109},
    year = {1988},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_16654.shtml},
}