@article{PismaZhETF.56.153,
    title = {Weak ferroelectricity in layered $A^3B^3C_2^6$ ferroelectric-semiconductor materials},
    author = {Allakhverdiev, K. R. and Salaev, F. M. and Mikailov, F. A. and Mamedov, T. S.},
    journal = {Письма в ЖЭТФ},
    volume = {56},
    issue = {3},
    pages = {153},
    year = {1992},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_19400.shtml},
}