Thought it might be nice to share refferences.
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Müller-Tomfelde, C. and Schremmer, C. 2008. Touchers and mousers: commonalities and differences in co-located collaboration with multiple input devices. In Proceeding of the Twenty-Sixth Annual SIGCHI Conference on Human Factors in Computing Systems (Florence, Italy, April 05 - 10, 2008). CHI ‘08. ACM, New York, NY, 1149-1152. DOI= http://doi.acm.org/10.1145/1357054.1357234
Gross, T., Fetter, M., and Liebsch, S. 2008. The cuetable: cooperative and competitive multi-touch interaction on a tabletop. In CHI ‘08 Extended Abstracts on Human Factors in Computing Systems (Florence, Italy, April 05 - 10, 2008). CHI ‘08. ACM, New York, NY, 3465-3470. DOI= http://doi.acm.org/10.1145/1358628.1358875
A Agarwal, S Izadi, M Chandraker, and A Blake. High precision multi-touch sensing on surfaces using overhead cameras. Second Annual IEEE International Workshop on Horizontal Interactive Human- Computer System, 2007.
H Benko, A Wilson, and P Baudisch. Precise selection techniques for multi-touch screens. Proceedings of the SIGCHI conference on Human Factors in computing systems, Jan 2006.
Bill Buxton. Multi-touch systems that i have known and loved. http://www.billbuxton.com/multitouchoverview.html. 2007.
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J Han. Low-cost multi-touch sensing through frustrated total internal reflection. Proceedings of the 18th annual ACM symposium on User interface software and technology, 2005.
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J Kim, J Park, H Kim, and C Lee. Hci (human computer interaction) using multi-touch tabletop display. Communications, Jan 2007.
T Moscovich. Multi-touch interaction. CHI ’06: CHI ’06 extended abstracts on Human factors in computing systems, Jan 2006.
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J Rekimoto. Smartskin: an infrastructure for freehand manipulation on interactive surfaces. Proceedings of the SIGCHI conference on Human factors in computing systems, Jan 2002.
K Ryall. Multi-user input for tabletop environments: Who is touching where, when. Workshop in ACM CSCW 2002 Conference on Computer Suported Cooperative Work, November, 2002, 2002.
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L Terrenghi, D Kirk, A Sellen, and S Izadi. Affordances for manipulation of physical versus digital media on interactive surfaces. Proceedings of the SIGCHI conference on Human factors in computing systems, Jan 2007.
A Toney and B Thomas. Considering reach in tangible and table top design. First IEEE International Workshop on Horizontal Interactive Human-Computer Systems, Jan 2006.
E Tse and S Greenberg. SDGToolkit: A toolkit for rapidly prototyping single display groupware. Poster in ACM CSCW ’2002 Conference on Computer Suported Cooperative Work, November, 2002.
W Westerman. Hand tracking, finger identification, and chordic manipulation on a multi-touch surface. PhD Thesis, University of Delaware, Jan 1999.
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A Wilson. PlayAnywhere: a compact interactive tabletop projectionvision system. Proceedings of the 18th annual ACM symposium on User interface software and technology, Jan 2005.