1.       Many software programs for recording and editing sounds can be found on the World Wide Web. An excellent free program is provided by Audacity (http://audacity.sourceforge.net/).

2.       J.A. White, M.J. Santos, A. González & S. Velasco, “Timing the oscillations of a mass-spring system“, The Physics Education, (in press).

3.       S. Velasco, M.J. Santos, A. González &, J.A. White, “Timing the oscillations of a pendulum“, The Physics Education, 46(3) 133-134 (March 2011).

4.       S. Ganci, “Measurement of g by means of the ‘improper’ use of sound card software: a multipurpose experiment,” Phys. Educ. 43(3), 297 (2008).

5.       J. A. White, F.L. Román, A. Medina, and S. Velasco, “A measurement of g listening to falling balls,” Phys. Teach. 45(3), 175 (2007).

6.       L. Hmurcik, A. Slacik, H. Miller, and S. Samoncik, “Linear regression analysis in a first physics lab,” Am. J. Phys. 57(2), 135 (1989).

7.       R. Dwayne, “An Inexpensive Computer-Controlled Photogate,” Phys. Teach. 43(3), 169 (2005)

8.      http://www.ptb.de/en/org/1/11/115/_index.htm