• Hiroshi Ishii, Brygg Ullmer, Tangible Bits: Towards seamless interfaces between people, bits and atoms, Proceedings of the SIGCHI conference on Human factors in computing systems, CHI’97, Atlanta, Georgia, United States: ACM press, pp. 234-241.

• Ishii, H., Mazalek, A., and Lee, J., Bottle as mini interface to access digital information, In proceedings of extended abstract on Human factors in computing,  CHI’01, New York, NY, USA: ACM press, pp. 187-188.

• Underkoffler, J., Ishii, H., Urp: a luminous-tangible workbench for urban planning and design, In proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit, CHI’99, New York, NY, USA: ACM press, pp. 386-393.

• Hornecker, E. (2006) The tangible interaction framework
http://www.ehornecker.de/TangiblesFramework.html#case [accessed 10.01.2012]

Image source:
Marble Answering Machine:
http://interactionthesis.wordpress.com/2007/02/01/marble-answering-machine/

Urban Planning Workbench (Urp):
http://www.inventinginteractive.com/2010/06/04/oblong-and-before/

Reactable:
http://en.wikipedia.org/wiki/Reactable