@article{10_2140_agt_2011_11_691,
     author = {Mattman, Thomas W},
     title = {Graphs of 20 edges are 2{\textendash}apex, hence unknotted},
     journal = {Algebraic and Geometric Topology},
     pages = {691--718},
     year = {2011},
     volume = {11},
     number = {2},
     doi = {10.2140/agt.2011.11.691},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2011.11.691/}
}