http://www.physicsclassroom.com/Class/waves/u10l4a.cfm [2]
http://en.wikipedia.org/wiki/Periodic_travelling_wave [3]
http://www.ams.org/journals/bull/1942-48-08/S0002-9904-1942-07721-4/S000... [4]
https://www.cis.rit.edu/class/simg303/Notes/Ch4-TravelingWaves.pdf [5]
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/trawvcon.html [6]
http://hyperphysics.phy-astr.gsu.edu/hbase/waves/wavsol.html [7]
http://web.utk.edu/~cnattras/Physics221Spring2013/modules/m10/traveling_... [8]
Links
[1] https://hootsgo.org/?q=node/6389
[2] http://www.physicsclassroom.com/Class/waves/u10l4a.cfm
[3] http://en.wikipedia.org/wiki/Periodic_travelling_wave
[4] http://www.ams.org/journals/bull/1942-48-08/S0002-9904-1942-07721-4/S0002-9904-1942-07721-4.pdf
[5] https://www.cis.rit.edu/class/simg303/Notes/Ch4-TravelingWaves.pdf
[6] http://hyperphysics.phy-astr.gsu.edu/hbase/sound/trawvcon.html
[7] http://hyperphysics.phy-astr.gsu.edu/hbase/waves/wavsol.html
[8] http://web.utk.edu/~cnattras/Physics221Spring2013/modules/m10/traveling_waves.htm