@article{PismaZhETF.87.81,
    title = {$2\gamma$ and $3\gamma$  annihilation as  calibration processes for high energy $e^+ e^-$-colliders},
    author = {Barto1, E. and Bakmaev, S. and Kuraev, E. A. and Shatnev, M. G. and Se1ansky, M.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {87},
    issue = {2},
    pages = {81},
    year = {2008},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_27974.shtml},
}