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2. Eigenvalues of a matrix inside an ellipse and Chebyshev filter;Ahn;IEEE Trans. on Automatic Control,1979
3. A simple test for zeros of a complex polynomial in a sector;Anderson;IEEE Trans. on Automatic Control,1979
4. The Schwarz-Christoffel transformation and polynomial root clustering;Bickart;Proc. of the 7th IFAC World Congress,1978
5. Feedback control theory;Doyle,1992