Zhang, Fuzhen (2005). Zhang, Fuzhen (ed.). The Schur Complement and Its Applications. Numerical Methods and Algorithms. Vol.4. Springer. doi:10.1007/b105056. ISBN0-387-24271-6.
Feshbach, Herman (1958). "Unified theory of nuclear reactions". Annals of Physics. 5 (4): 357–390. doi:10.1016/0003-4916(58)90007-1.