%0 Journal Article %A Fong, C. K. %A Sourour, A. R. %T On the Operator Identity ∑ AkXBk ≡ 0 %J Canadian journal of mathematics %D 1979 %P 845-857 %V 31 %N 4 %U http://geodesic.mathdoc.fr/articles/10.4153/CJM-1979-080-x/ %R 10.4153/CJM-1979-080-x %F 10_4153_CJM_1979_080_x