@article{PismaZhETF.43.126,
    title = {Exciton absorption in disordered crystals with a singular spectrum (the Urbach problem)},
    author = {Kusmartsev, F. V. and Shchukin, V. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {43},
    issue = {3},
    pages = {126},
    year = {1986},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_21259.shtml},
}