@article{10_4153_CJM_1976_108_4,
     author = {Kemp, R. R. D. and Lee, S. J.},
     title = {Finite {Dimensional} {Perturbations} of {Differential} {Expressions}},
     journal = {Canadian journal of mathematics},
     pages = {1082--1104},
     year = {1976},
     volume = {28},
     number = {5},
     doi = {10.4153/CJM-1976-108-4},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1976-108-4/}
}