Links
[1] https://hootsgo.org/?q=node/6405
[2] http://en.wikipedia.org/wiki/Simple_harmonic_motion
[3] http://hyperphysics.phy-astr.gsu.edu/hbase/shm.html
[4] http://www.animations.physics.unsw.edu.au/mechanics/chapter4_simpleharmonicmotion.html
[5] http://www.britannica.com/EBchecked/topic/545322/simple-harmonic-motion
[6] http://www.sparknotes.com/physics/oscillations/oscillationsandsimpleharmonicmotion/section2.rhtml
[7] http://www.sparknotes.com/physics/oscillations/oscillationsandsimpleharmonicmotion/problems_1.html
[8] http://www.kwantlen.ca/science/physics/faculty/mcoombes/P1120_Solutions/Set_12/P1120_12_Solutions.htm
[9] http://www.newhavenscience.org/physics/answershoproblems.htm
[10] http://physics.doane.edu/hpp/Resources/Fuller3/pdf/F3Chapter_15.pdf
[11] http://slxy.cqupt.edu.cn/admin/upload/teachermounts/1289961141.pdf
[12] http://www.d.umn.edu/~rlindek1/me3230/Ch%208_Waldren.pdf
[13] http://academic.udayton.edu/LenoPedrotti/examples/206Springs.pdf
[14] http://web.mit.edu/8.01t/www/materials/ProblemSets/Raw/f12/ps11sol.pdf
[15] http://web.mit.edu/8.01t/www/materials/modules/chapter23.pdf