@article{10_4153_CJM_2005_010_1,
     author = {Booss-Bavnbek, Bernhelm and Lesch, Matthias and Phillips, John},
     title = {Unbounded {Fredholm} {Operators} and {Spectral} {Flow}},
     journal = {Canadian journal of mathematics},
     pages = {225--250},
     year = {2005},
     volume = {57},
     number = {2},
     doi = {10.4153/CJM-2005-010-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-2005-010-1/}
}