@article{JOLT_2004_14_1_a5,
     author = {Brigitte E. Breckner and Wolfgang A. F. Ruppert},
     title = {On {Compactification} {Lattices} of {Subsemigroups} of {SL(2,} {R)}},
     journal = {Journal of Lie Theory},
     pages = {73--109},
     year = {2004},
     volume = {14},
     number = {1},
     url = {http://geodesic.mathdoc.fr/item/JOLT_2004_14_1_a5/}
}