cement-texture-dark.jpg source=http://www.public-domain-image.com/full-image/textures-and-patterns-public-domain-images-pictures/concrete-texture-public-domain-images-pictures/cement-texture.jpg-royalty-free-stock-image.html license=public domain
chamber-pool-icon.png source=PhET notes=created by gruneich
grass-texture.png source=Open Clip Art notes=http://openclipart.org/detail/21212/grass-texture-by-rg1024-21212 as public domain
handle.png source=PhET notes=drawn by NP
mass.png source=PhET notes=NP or AP
mystery-pool-icon.png source=PhET notes=created by gruneich
square-pool-icon.png source=PhET notes=created by gruneich
trapezoid-pool-icon.png source=PhET notes=created by gruneich