Enumerating Regular Expressions and Their Languages. - Jonathan Lee 005; Jeffrey O. Shallit (CIAA, 2004)

Enumerating regular expressions and their languages - Hermann Gruber; Jonathan Lee 005; Jeffrey O. Shallit (CoRR, 2012)

Enumerating regular expressions and their languages. - Hermann Gruber; Jonathan Lee 005; Jeffrey O. Shallit (Handbook of Automata Theory (I.), 2021)