Zill, D. G., Wright, W. S., & Wright, C. D. (2001). Complete solutions manual for Zill's a first course in differential equations with modeling applications and Zill & Cullen's diffrential wquations with boundary-value problems (7th ed. & 5th ed.). Pacific Grove, U. S. A.: Brooks/Cole Thomson Learning.

Zill, Dennis G., Warren S. Wright, and Carol D. Wright. Complete Solutions Manual for Zill's a First Course in Differential Equations With Modeling Applications and Zill & Cullen's Diffrential Wquations With Boundary-value Problems. 7th ed. & 5th ed. Pacific Grove, U. S. A.: Brooks/Cole Thomson Learning, 2001.

Zill, Dennis G., Warren S. Wright, and Carol D. Wright. Complete Solutions Manual for Zill's a First Course in Differential Equations With Modeling Applications and Zill & Cullen's Diffrential Wquations With Boundary-value Problems. 7th ed. & 5th ed. Pacific Grove, U. S. A.: Brooks/Cole Thomson Learning, 2001.