[1] HILDEBRANDT R.: Trennung von Mengen mittels konvexer Funktionen. Diplomarbeit, TH Ilmenau 1980.
[2] HILDEBRANDT R., NEHSE B.: Separation by convex functionals. Conf. on Math. Programming, Eisenach 1980, Abstracts (to appear).
[3] HOLMES R. B.: 
Geometric Functional Analysis and its Applications. Springer-Verlag, New York - Heidelberg - Berlin 1975. 
MR 0410335 | 
Zbl 0336.46001 
[4] KANTOROWITSCH L. W., AKILOV G. P.: 
Functional. Analysis. Nauka, Moscow 1977 (in Russian). 
MR 0511615 
[5] KÖTHE G.: 
Topologische lineare Räume I. Springer-Verlag, Berlin - Heidelberg - New York 1966. 
MR 0194863 
[6] NEHSE R.: 
Problems in connection with the Hahn-Banach-Theorem. Proc. of the Summer-school "Nonlinear Analysis", Berlin 1979, Akad. Verlag (to appear). 
MR 0639925