Leonard M. Adleman Qi Cheng Ashish Goel Ming-Deh A. Huang David Kempe Pablo Moisset de Espanés Paul W. K. Rothemund Combinatorial optimization problems in self-assembly. 23-32 2002 conf/stoc/2002 STOC http://doi.acm.org/10.1145/509907.509913 db/conf/stoc/stoc2002.html#AdlemanCGHKER02