@article{PismaZhETF.16.197,
    title = {Quantum Theory without the Superposition Principle},
    author = {Shapiro, I. S.},
    journal = {Письма в ЖЭТФ},
    volume = {16},
    issue = {3},
    pages = {197},
    year = {1972},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_26769.shtml},
}