@article{10_4153_CMB_2010_065_9,
     author = {Birkenmeier, Gary F. and Park, Jae Keol and Rizvi, S. Tariq},
     title = {Hulls of {Ring} {Extensions}},
     journal = {Canadian mathematical bulletin},
     pages = {587--601},
     year = {2010},
     volume = {53},
     number = {4},
     doi = {10.4153/CMB-2010-065-9},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2010-065-9/}
}