An ordered set of arithmetic functions representing the least ε-number. - Hilbert Levitz (Math. Log. Q., 1975)

Calculation of an Order Type: An application of Non-Standard Methods. - Hilbert Levitz (Math. Log. Q., 1982)

Decidability of some Problems Pertaining to Base 2 Exponential Diophantine Equations. - Hilbert Levitz (Math. Log. Q., 1985)

Classification of Quantifier Prefixes Over Exponential Diophantine Equations. - James P. Jones; Hilbert Levitz; A. J. Wilkie (Math. Log. Q., 1986)

Eine Rekursive Universelle Funktion Für Die Primitiv-Rekursiven Funktionen. - Hilbert Levitz; Warren D. Nichols (Math. Log. Q., 1987)

A Natural Variant of Ackermann's Function. - Hilbert Levitz; Warren D. Nichols (Math. Log. Q., 1988)

A Macro Program for the Primitive Recursive Functions. - Hilbert Levitz; Warren D. Nichols; Robert F. Smith (Math. Log. Q., 1991)

On Series of Ordinals and Combinatorics. - James P. Jones; Hilbert Levitz; Warren D. Nichols (Math. Log. Q., 1997)