TY - JOUR AU - Brumfield, G. AU - Hilden, Hugh Michael AU - Lozano Imízcoz, María Teresa AU - Montesinos Amilibia, José María AU - Ramírez Losada, E. AU - Short, H. AU - Tejada Cazorla, Juan Antonio AU - Toro, M. PY - 2008 SN - 1405-213X UR - https://hdl.handle.net/20.500.14352/50710 T2 - Boletín de la Sociedad Matemática Mexicana. Tercera Serie AB - It has been shown [H. M. Hilden et al., Invent. Math. 87 (1987), no. 3, 441–456;] that the orbifold group U of the Borromean rings with singular angle 90 degrees is universal, i.e. for every closed orientable 3-manifold M3 there is a finite index... LA - eng M2 - 283 PB - Sociedad Matemática Mexicana KW - 3-manifold KW - orbifold KW - branched covering KW - universal link KW - universal group TI - On finite index subgroups of a universal group TY - journal article VL - 14 ER -