@article{GT_2008_12_4_a4,
     author = {Lackenby, Marc and Long, Darren D and Reid, Alan W},
     title = {LERF and the {Lubotzky{\textendash}Sarnak} {Conjecture}},
     journal = {Geometry & topology},
     pages = {2047--2056},
     publisher = {mathdoc},
     volume = {12},
     number = {4},
     year = {2008},
     doi = {10.2140/gt.2008.12.2047},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/gt.2008.12.2047/}
}