@article{PismaZhETF.59.202,
    title = {Composite operators for a BCS superconductor},
    author = {Bonca, J. and Balatsky, A. V.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {59},
    issue = {3},
    pages = {202},
    year = {1994},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_19596.shtml},
}