Celina M. Herrera de Figueiredo Guilherme Dias da Fonseca Vinícius G. P. de Sá Jeremy Spinrad Algorithms for the Homogeneous Set Sandwich Problem. 149-180 2006 46 Algorithmica 2 http://dx.doi.org/10.1007/s00453-005-1198-2 db/journals/algorithmica/algorithmica46.html#FigueiredoFSS06