1. Akemann C.A.: Left ideal structure of C*-algebras. J. Funct. Anal. 6, 305–317 (1970)
2. Awodey, S.: Category Theory, Oxford Logic Guides, vol. 52, 2nd edn. Oxford University Press, Oxford (2010)
3. Comman H.: Upper regularization for extended self-adjoint operators. J. Oper. Theory 55(1), 91–116 (2006)
4. Birkhoff, G.: Lattice Theory, 3rd edn. American Mathematical Society (1967)
5. Brown L.G.: Semicontinuity and multipliers of C*-algebras. Can. J. Math. XL(4), 865–988 (1988)