@article{10_4153_CJM_2011_092_x,
     author = {Brown, Lawrence G. and Lee, Hyun Ho},
     title = {Homotopy {Classification} of {Projections} in the {Corona} {Algebra} of a {Non-simple} {C*-algebra}},
     journal = {Canadian journal of mathematics},
     pages = {755--777},
     year = {2012},
     volume = {64},
     number = {4},
     doi = {10.4153/CJM-2011-092-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-2011-092-x/}
}