Truong Kieu Linh Atsushi Imiya Robin Strand Gunilla Borgefors Supercover of Non-square and Non-cubic Grids. 88-97 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3322&spage=88 2004 conf/iwcia/2004 IWCIA db/conf/iwcia/iwcia2004.html#LinhISB04