25432 Yuji Kobayashi: Note on compatible well orders on a free monoid.
Semigroup Forum 45 (1992), 23-25.

25433 Yuji Kobayashi: Well-ordered monoids - two numerical functions.
Internet 2004, 10p.

25434 Joseph Kruskal: The theory of well-quasi-ordering - a frequently
discovered concept. J. Comb. Theory A 13 (1972), 297-305.