@article{10_4153_CMB_1992_040_7,
     author = {Barr, Michael and Wells, Charles},
     title = {On the {Limitations} of {Sketches}},
     journal = {Canadian mathematical bulletin},
     pages = {287--294},
     year = {1992},
     volume = {35},
     number = {3},
     doi = {10.4153/CMB-1992-040-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1992-040-7/}
}