@article{1178245177,
author = {Umegaki, Hisaharu},
title = {Conditional expectation in an operator algebra, I},
journal = {Tohoku Math. J. (2)},
volume = {6},
number = {2-3},
year = {1954},
pages = { 177-181},
language = {en},
url = {http://dml.mathdoc.fr/item/1178245177}
}
Umegaki, Hisaharu. Conditional expectation in an operator algebra, I. Tohoku Math. J. (2), Tome 6 (1954) no. 2-3, pp. 177-181. http://gdmltest.u-ga.fr/item/1178245177/