Harry B. Hunt III, Thomas G. Szymanski. Lower Bounds and Reductions Between Grammar Problems. Journal of the ACM, 25(1):32-51, 1978. [doi]
@article{HuntS78,
title = {Lower Bounds and Reductions Between Grammar Problems},
author = {Harry B. Hunt III and Thomas G. Szymanski},
year = {1978},
doi = {10.1145/322047.322051},
url = {http://doi.acm.org/10.1145/322047.322051},
tags = {grammar},
researchr = {https://researchr.org/publication/HuntS78},
cites = {0},
citedby = {0},
journal = {Journal of the ACM},
volume = {25},
number = {1},
pages = {32-51},
}