Journal of Computer and System SciencesVolume 7, Issue 6, December 1973, Pages 583-596Two iteration theorems for some families of languagesAuthor links open overlay panelL. BoassonShow moreShareCitehttps://doi.org/10.1016/S0022-0000(73)80036-4Get rights and contentUnder an Elsevier user licenseopen archivePrevious article in issueNext article in issueRecommended articlesCited by (0)Copyright © 1973 Published by Elsevier Inc.