Jonathan Goldstine. A simplified proof of Parikh's theorem. Discrete Mathematics, 19(3):235-239, 1977. [doi]
@article{Goldstine77-0,
title = {A simplified proof of Parikh's theorem},
author = {Jonathan Goldstine},
year = {1977},
doi = {10.1016/0012-365X(77)90103-0},
url = {http://dx.doi.org/10.1016/0012-365X(77)90103-0},
researchr = {https://researchr.org/publication/Goldstine77-0},
cites = {0},
citedby = {0},
journal = {Discrete Mathematics},
volume = {19},
number = {3},
pages = {235-239},
}