1. On extendibility of unavoidable sets;Choffurt;Lecture Notes in Computer Science,1984
2. Subword topology;Dare;Theoretical Computer Science,1983
3. A Generalization of the Parikh Vector for finite and infinite finite words;Dare;Lecture Notes in Computer Science,1985
4. Introduction to Formal Language Theory;Harrison,1978
5. Infinite words, infinite trees and infinite computations;Nivat;Mathematical Centre Tracts,1979