1. Clay—Wikipedia (2017).
http://en.wikipedia.org/wiki/clay
2. Clay—Wikipedia (2017).
http://en.wikipedia.org/wiki/Clay_minerals
3. S. Guggenheim, R.T. Martin, Clays Clay Miner. 43, 255 (1995)
4. Brick—Wikipedia (2017).
http://en.wikipedia.org/wiki/Brick
5. Brick history—Brick directory.
www.brickdidectory.co.uk/html/brick_history.html