@article{10_4153_CJM_1981_013_8,
     author = {Espelie, M. Solveig and Joseph, James E.},
     title = {Some {Properties} of {\ensuremath{\theta}-Closure}},
     journal = {Canadian journal of mathematics},
     pages = {142--149},
     year = {1981},
     volume = {33},
     number = {1},
     doi = {10.4153/CJM-1981-013-8},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1981-013-8/}
}