@article{PismaZhETF.55.635,
    title = {Role of hybridization in the polaron mechanism for the formation of $U^-$ centers, soft potentials, and two-well potentials},
    author = {Tsendin, K. D.},
    journal = {Письма в ЖЭТФ},
    volume = {55},
    issue = {11},
    pages = {635},
    year = {1992},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_19329.shtml},
}