Meduna, Alexander. “Economical Transformations of Phrase-Structure Grammars to Scattered Context Grammars”. Acta Cybernetica 13, no. 3 (January 1, 1998): 225-242. Accessed October 7, 2022. https://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3489.