@article{PismaZhETF.11.46,
    title = {Causality and Scattering of Wave Packets},
    author = {Khalfin, L. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {11},
    issue = {1},
    pages = {46},
    year = {1970},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_26052.shtml},
}