Gennaro Costagliola, Amy J. Ko, Allen Cypher, Jeffrey Nichols, Christopher Scaffidi, Caitlin Kelleher, Brad A. Myers: 2011 IEEE Symposium on Visual Languages and Human-Centric Computing, VL/HCC 2011, Pittsburgh, PA, USA, September 18-22, 2011. IEEE 2011, ISBN 978-1-4577-1246-3