URL: Tampera and pigment

http://www.wellesley.edu/Chemistry/Chem&Art/Topics/Pigments_Painting/pigments_painting.html

http://www.webexhibits.org/pigments/intro/index.htm

http://www.paintmaking.com/grinding_egg_tempera.htm

http://realcolorwheel.com/1mediums.htm

http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/rocks_metals/1_paints_pigments2.shtml