@article{PismaZhETF.3.129,
    title = {Concerning the Decay $K_L^0\to\pi^+ \pi^-$},
    author = {Khalfin, L. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {3},
    issue = {3},
    pages = {129},
    year = {1966},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_24705.shtml},
}