Martha Mercaldi Steven Swanson Andrew Petersen Andrew Putnam Andrew Schwerin Mark Oskin Susan J. Eggers Modeling instruction placement on a spatial architecture. 158-169 2006 conf/spaa/2006 SPAA http://doi.acm.org/10.1145/1148109.1148137 db/conf/spaa/spaa2006.html#MercaldiSPPSOE06