@article{10_2140_agt_2002_2_743,
     author = {Niblo, Graham A and Williams, Ben T},
     title = {Engulfing in word-hyperbolic groups},
     journal = {Algebraic and Geometric Topology},
     pages = {743--755},
     year = {2002},
     volume = {2},
     number = {2},
     doi = {10.2140/agt.2002.2.743},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2002.2.743/}
}