KLB Book 3 http://en.m.wikipedia.org/wiki/Ripple_tank https://www.miniphysics/ripple-tank.html http://www.falstad.com/ripple/ https://www.physicsclassroom.com/class/waves/Lesson-3/Reflection https://www.s-cool.co.uk/gcse/physics/properties-of waves/revise-it/reflection-of waves