@article{10_4153_CMB_1964_010_5,
     author = {Duff, G.F.D.},
     title = {On the {Principle} of {Superposition} in {Quantum} {Mechanics}},
     journal = {Canadian mathematical bulletin},
     pages = {77--83},
     year = {1964},
     volume = {7},
     number = {1},
     doi = {10.4153/CMB-1964-010-5},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1964-010-5/}
}