@article{10_4153_CJM_1971_050_7,
     author = {Friedman, N. A. and Tong, A. E.},
     title = {On {Additive} {Operators}},
     journal = {Canadian journal of mathematics},
     pages = {468--480},
     year = {1971},
     volume = {23},
     number = {3},
     doi = {10.4153/CJM-1971-050-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1971-050-7/}
}