1. Conditions for positive and nonnegative definiteness in terms of pseudoinverses;Albert;SIAM J. Appl. Math.,1969
2. J.K. Baksalary, Algebraic characterizations and statistical implications of the commutativity of orthogonal projectors, in: T. Pukkila, S. Puntanen (Eds.), Proceedings of the Second International Tampere Conference in Statistics, University of Tampere, Tampere, Finland, 1987, pp. 113–142
3. Idempotency of linear combinations of two idempotent matrices;Baksalary;Linear Algebra Appl.,2000
4. A generalization of the Schur complement by means of the Moore–Penrose inverse;Carlson;SIAM J. Appl. Math.,1974
5. Natural structures on semigroups with involution;Drazin;Bull. Amer. Math. Soc.,1978