1. On normal derivations;J. Anderson;Proceedings of the American Mathematical Society,1973
2. Generalized Fuglede-Putnam's theorem and orthogonality;A. Bachir;Australian Journal of Mathematical Analysis and Applications,2004
3. An asymmetric Fuglede-Putnam's theorem and orthogonality;A. Bachir;Kyungpook Mathematical Journal,2006
4. Generalized derivation;A. Bachir;Sciences University of Tokyo (SUT) Journal of Mathematics,2004
5. Orthogonality in linear metric spaces;G. Birkhoff;Duke Mathematical Journal,1935