@article{10_2140_agt_2001_1_411,
     author = {Neumann, Walter D},
     title = {Immersed and virtually embedded \ensuremath{\pi}1{\textendash}injective surfaces in graph manifolds},
     journal = {Algebraic and Geometric Topology},
     pages = {411--426},
     year = {2001},
     volume = {1},
     number = {1},
     doi = {10.2140/agt.2001.1.411},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2001.1.411/}
}