@article{GT_2009_13_3_a7,
     author = {Clark, David and Morrison, Scott and Walker, Kevin},
     title = {Fixing the functoriality of {Khovanov} homology},
     journal = {Geometry & topology},
     pages = {1499--1582},
     publisher = {mathdoc},
     volume = {13},
     number = {3},
     year = {2009},
     doi = {10.2140/gt.2009.13.1499},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/gt.2009.13.1499/}
}