@article{JETPL.113.410,
    title = {Fock?Schwinger Method in the Case of Different Masses},
    author = {Osipov, A. A.},
    journal = {JETP Lett.},
    volume = {113},
    issue = {6},
    pages = {413},
    year = {2021},
    doi = {10.1134/S0021364021060096},
    url = {http://jetpletters.ru/ps/dx/10.31857/S123456782106001X},
    note = {[Pisma v ZhETF 113, 410 (2021)]}
}