1. Commutators on ℓp spaces;Apostol;Rev. Roumaine Math. Appl.,1972
2. On the left essential spectrum and non-cyclic operators in Banach spaces;Apostol;Rev. Roumaine Math. Appl.,1972
3. Commutators on c0-spaces and on ℓ∞-spaces;Apostol;Rev. Roumaine Math. Pures Appl.,1973
4. Structure of commutators of operators;Brown;Ann. of Math.,1965
5. Subspaces of L1 containing L1;Enflo;Studia Math.,1979