@article{10_4153_CJM_2015_038_7,
     author = {Phillips, John and Raeburn, Iain},
     title = {Centre-valued {Index} for {Toeplitz} {Operators} with {Noncommuting} {Symbols}},
     journal = {Canadian journal of mathematics},
     pages = {1023--1066},
     year = {2016},
     volume = {68},
     number = {5},
     doi = {10.4153/CJM-2015-038-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-2015-038-7/}
}