@inproceedings{Schaefer_1978,
    doi = {10.1145/800133.804350},
    url = {https://doi.org/10.1145%2F800133.804350},
    year = {1978},
    publisher = {{ACM} Press},
    author = {Thomas J. Schaefer},
    title = {The complexity of satisfiability problems},
    booktitle = {Proceedings of the tenth annual {ACM} symposium on Theory of computing  - {STOC} {\textquotesingle}78}
}

@inproceedings{Schaefer_1978, doi = {10.1145/800133.804350}, url = {https://doi.org/10.1145%2F800133.804350}, year = {1978}, publisher = {{ACM} Press}, author = {Thomas J. Schaefer}, title = {The complexity of satisfiability problems}, booktitle = {Proceedings of the tenth annual {ACM} symposium on Theory of computing - {STOC} {\textquotesingle}78} }