@article{PismaZhETF.33.24,
    title = {Hyperfine interaction as a reason for removing the forbiddenness of a phononless transition in an impurity center},
    author = {Ellervee',  and Laisaar, A. I. and Oper, A. M. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {33},
    issue = {1},
    pages = {24},
    year = {1981},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_22921.shtml},
}