@article{10_4153_CMB_2010_039_x,
     author = {Porter, Jack and Tikoo, Mohan},
     title = {Separating {H-sets} by {Open} {Sets}},
     journal = {Canadian mathematical bulletin},
     pages = {360--366},
     year = {2010},
     volume = {53},
     number = {2},
     doi = {10.4153/CMB-2010-039-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2010-039-x/}
}