@article{BMMS_2011_34_3_a8,
     author = {Hee Sik Kim and Kyoung Ja Lee},
     title = {Extended {Upper} {Sets} in $BE${-Algebras}},
     journal = {Bulletin of the Malaysian Mathematical Society},
     year = {2011},
     volume = {34},
     number = {3},
     url = {http://geodesic.mathdoc.fr/item/BMMS_2011_34_3_a8/}
}