@inproceedings{Cheung_1995,
    doi = {10.1145/315891.315991},
    url = {https://doi.org/10.1145%2F315891.315991},
    year = {1995},
    publisher = {{ACM} Press},
    author = {Bruce S. N. Cheung},
    title = {Ambiguity in context-free grammars},
    booktitle = {Proceedings of the 1995 {ACM} symposium on Applied computing  - {SAC} {\textquotesingle}95}
}

@inproceedings{Cheung_1995, doi = {10.1145/315891.315991}, url = {https://doi.org/10.1145%2F315891.315991}, year = {1995}, publisher = {{ACM} Press}, author = {Bruce S. N. Cheung}, title = {Ambiguity in context-free grammars}, booktitle = {Proceedings of the 1995 {ACM} symposium on Applied computing - {SAC} {\textquotesingle}95} }