J. Duncan

Numerical Ranges II

F. Bonsall, J. Duncan, 1973 .

Complete Normed Algebras

F. Bonsall, J. Duncan, 1973 .

Numerical Ranges of Operators on Normed Spaces and of Elements of Normed Algebras: Hermitian elements of a complex unital Banach algebra

J. Duncan, F. Bonsall, J. Duncan, 1971 .

Dual representations of Banach algebras

F. Bonsall, J. Duncan, 1967 .

Nonlinear conditions for differentiability of functions

S. Krantz, J. Duncan, H. Parks, 1985 .