Momot, I. V. “Geometric Form of the Hahn–Banach Theorem for Generalized Convexity”.
Ukrains’kyi Matematychnyi Zhurnal
, vol. 55, no. 2, Feb. 2003, p. 284=287,
https://umj.imath.kiev.ua/index.php/umj/article/view/3906
.