@article{PismaZhETF.43.319,
    title = {Two- and three-loop amplitudes in boson string theory},
    author = {Belavin, A. A. and Knizhnik, V. G. and Morozov, A. Yu. and Perelomov, A. M.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {43},
    issue = {7},
    pages = {319},
    year = {1986},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_21334.shtml},
}