Hee-Kap Ahn Sang Won Bae Siu-Wing Cheng Kyung-Yong Chwa Casting an Object with a Core. 72-88 2009 54 Algorithmica 1 http://dx.doi.org/10.1007/s00453-007-9120-8 db/journals/algorithmica/algorithmica54.html#AhnBCC09