@article{PismaZhETF.21.121,
    title = {Soft mode at the boundary of the Brillouin zone and nature of the phase transition in monovalent mercury-halide crystals},
    author = {Barta, I. I. and Kaplyanskii, A. A. and Kulakov, V. V. and Markov, Yu. F.},
    journal = {Письма в ЖЭТФ},
    volume = {21},
    issue = {2},
    pages = {121},
    year = {1975},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_22264.shtml},
}