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Structure of the Solution Space of Certain Linear Equations, JDE 59(1985), 229 242 (with G.J. Etgen and G.D. Jones)
On the Factorization of Ordinary Linear Differential Operations, TAMS 297(1986), 717 728 (with G.J. Etgen and G.D. Jones)
Asymptotic Behavior of Solutions of a Third Order Difference Equation Portgualiae Mathematica 44(1987), 113 117 (with B. Smith)
Fourth Order Difference Equations: Oscillation and Nonoscillation, Rocky Mountain Journal of Mathematics 23(1993), 781 795
Oscillation Properties of Nonlinear Difference Equation, Portugaliae Mathematica 52(1995), 15 24 (with M. Sun)
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