Gaps between Connected Finite Graphs. - Robert Baldinger; Jonathan P. McCammond (Int. J. Algebra Comput., 1992)

Undecidability of the Identity Problem for Finite Semigroups. - Douglas Albert; Robert Baldinger; John Rhodes 001 (J. Symb. Log., 1992)

Gaps in the Categories of Finite Directed and Finite Transitive Graphs. - Robert Baldinger; Jonathan P. McCammond (Int. J. Algebra Comput., 1998)