1. Alefeld, G., Herzberger, J.: Introduction to interval computations. New York: Academic Press 1983.
2. Atanassova, L.: On the R-order of a single-step Nourein type method. In: Atanassova, L., Herzberger, J. (eds.) Computer arithmetic and enclosure methods, pp. 179 – 187. Amsterdam: Elsevier (North-Holland) 1992.
3. Atanassova, L., Herzberger, J.: A general approach to simultaneous inclusion methods for polynomial zeros. In: Atanassova, L., Herzberger J. (eds.) Computer arithmetic and enclosure methods, pp. 189 – 198. Amsterdam: Elsevier (North-Holland) 1992.
4. Atanassova, L., Herzberger, J.: Bemerkungen zur allgemeinen Darstellung von simultanen Polynomwurzel-Einschließungsverfahren. ZAMM 73 (in press).
5. Burmeister, W., Schmidt, J.W.: Determination of the cone radius for positive concave operators. Computing 33, 37 – 49 (1984).