1. Simple CMOS analog square-rooting and squaring circuits;Filanovsky;IEEE Trans. Circuits Syst. I,1992
2. H.T. Davis, Introduction to Nonlinear Differential and Integral Equations, in: Dover Books on Mathematics, New York, 1962.
3. An Introduction To Difference Equations;Elaydi,2005
4. A Schur method for the square root of a matrix;Björck,1983
5. Matrix Analysis;Horn,2013