@article{10_4153_CMB_1990_041_3,
     author = {Zaharopol, Radu},
     title = {On {Products} of {Conditional} {Expectation} {Operators}},
     journal = {Canadian mathematical bulletin},
     pages = {257--260},
     year = {1990},
     volume = {33},
     number = {3},
     doi = {10.4153/CMB-1990-041-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1990-041-3/}
}