Jose C. Ciria Eladio Domínguez Angel R. Francés Separation Theorems for Simplicity 26-Surfaces. 45-56 2002 conf/dgci/2002 DGCI http://link.springer.de/link/service/series/0558/bibs/2301/23010045.htm db/conf/dgci/dgci2002.html#CiriaDF02