Aldo de Luca, Stefano Varricchio. A positive pumping condition for regular sets. Bulletin of the EATCS, 39:171-174, 1989.
@article{LucaV89, title = {A positive pumping condition for regular sets}, author = {Aldo de Luca and Stefano Varricchio}, year = {1989}, researchr = {https://researchr.org/publication/LucaV89}, cites = {0}, citedby = {0}, journal = {Bulletin of the EATCS}, volume = {39}, pages = {171-174}, }