1. Some properties of matrix partial orderings;Baksalary;Linear Algebra Appl.,1989
2. Generalized Inverses: Theory and Applications;Ben-Israel,1974
3. Generalized Inverses of Linear Transformations;Campbell,1979
4. Normal partial isometries closed under multiplication on unitary spaces;Erdelyi;Lincei Rend. Sci. Fis. Mat. e Nat.,1968
5. J. Groβ, J. Hauke, and A. Markiewicz, Characterizations of partial orderings via a new preordering, Linear Algebra Appl., submitted for publication.