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2. R. Resnick, D. Halliday, and K. S. Krane, Physics, 5th ed., Vol. 1 (Wiley, 2002), p. 105.
3. J. Walker, The Flying Circus of Physics, 2nd ed. (Wiley, 2007), p. 66.
4. L. Kirkpatrick and G. E. Francis, Physics: A Conceptual World View, 7th ed. (Brooks/Cole Cengage Learning, 2010), p. 178.