1.
Aceto L, Fokkink W, Ingólfsdóttir A. On a Question of Arto Salomaa: The Equational Theory of Regular Expressions over a Singleton Alphabet is not Finitely Based. BRICS [Internet]. 1996Jun.6 [cited 2019Dec.13];3(36). Available from: https://tidsskrift.dk/brics/article/view/20018