@article{10_4153_CMB_1980_022_3,
     author = {Joseph, James E.},
     title = {Multifunctions and {Inverse} {Cluster} {Sets}},
     journal = {Canadian mathematical bulletin},
     pages = {161--171},
     year = {1980},
     volume = {23},
     number = {2},
     doi = {10.4153/CMB-1980-022-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1980-022-3/}
}