@article{PismaZhETF.15.102,
    title = {Negative Differential Conductivity of a Two-valley Semiconductor Having No Negative Section of the V(E) Characteristic},
    author = {Prokhorov, E. D. and Beletskii, N. I.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {15},
    issue = {2},
    pages = {102},
    year = {1972},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_26499.shtml},
}