@article{10_4153_CMB_1983_023_7,
     author = {Heinrich, Katherine},
     title = {Covering {Problem} for {Idempotent} {Latin} {Squares}},
     journal = {Canadian mathematical bulletin},
     pages = {144--148},
     year = {1983},
     volume = {26},
     number = {2},
     doi = {10.4153/CMB-1983-023-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1983-023-7/}
}