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
drain-faucet-attached.png source=PhET notes = created by SR from images provided by NP
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
knob.png source=PhET notes=drawn by NP
mass.png source=PhET notes=NP or AP
nozzle.png source=PhET notes=created by SR based on work by NP
panel.png source=PhET notes = created by SR
pipe_handle_1.png source=PhET notes=NP
pipe-left-back.png source=created by ON
pipe-left-front.png source=created by ON
pipe-middle.png source=PhET notes=created by ON
pipe-right.png source=PhET notes=created by ON