[BCB] Robert L. Borrelli, Courtney Coleman, and William E. Boyce, Differential Equations
Laboratory Workbook, Wiley, New York, 1992.

[HW] J. Hubbard and B. West, Differential Equations, A Dynamical Systems Approach,
Part I, Texts in Applied Mathematics Vol 5, Springer Verlag, 1991.

[SW1] Dan Schwalbe and Stan Wagon, Nullclines and equilibria, fish and balloons,
Mathematica in Education and Research 4:4 (1995).

[SW2] Dan Schwalbe and Stan Wagon, VisualDSolve: New Frontiers in the Visualization of
Differential Equations, Springer/TELOS, 1996, forthcoming.

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