Cantor, David G.. On The Ambiguity Problem of Backus Systems. J. ACM, 9(4), 1962. [doi]
@article{cantor62-0, title = {On The Ambiguity Problem of Backus Systems}, author = {Cantor, David G.}, year = {1962}, doi = {10.1145/321138.321145}, url = {http://doi.acm.org/10.1145/321138.321145}, researchr = {https://researchr.org/publication/cantor62-0}, cites = {0}, citedby = {0}, journal = {J. ACM}, volume = {9}, number = {4}, }