Reference:

O. Burkart and J. Esparza. More infinite results. Bulletin of the EATCS 62 (Concurrency Column), 1997.

Suggested BibTeX entry:

@article{BE97,
    author = {O. Burkart and J. Esparza},
    journal = {Bulletin of the EATCS 62 (Concurrency Column)},
    title = {More Infinite Results},
    year = {1997}
}