@article{10_4153_CMB_1971_106_2,
     author = {Shultz, Harris S.},
     title = {Multiplication of {Operators} by {C} \ensuremath{\infty} {Functions}},
     journal = {Canadian mathematical bulletin},
     pages = {579--581},
     year = {1971},
     volume = {14},
     number = {4},
     doi = {10.4153/CMB-1971-106-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1971-106-2/}
}