@article{Ajtai_1987,
    doi = {10.1145/31846.31852},
    url = {https://doi.org/10.1145%2F31846.31852},
    year = {1987},
    month = {oct},
    publisher = {Association for Computing Machinery ({ACM})},
    volume = {34},
    number = {4},
    pages = {1004--1015},
    author = {Miklos Ajtai and Yuri Gurevich},
    title = {Monotone versus positive},
    journal = {Journal of the {ACM}}
}

@article{Ajtai_1987, doi = {10.1145/31846.31852}, url = {https://doi.org/10.1145%2F31846.31852}, year = {1987}, month = {oct}, publisher = {Association for Computing Machinery ({ACM})}, volume = {34}, number = {4}, pages = {1004--1015}, author = {Miklos Ajtai and Yuri Gurevich}, title = {Monotone versus positive}, journal = {Journal of the {ACM}} }