@Book{Heuser:1986,
author = {H. Heuser},
title = {Funktionalanalysis: Theorie und Anwendung},
publisher = {Teubner},
year = 1986
}
@InCollection{Narici:1996,
author = {L. Narici and E. Beckenstein},
title = {The {Hahn-Banach Theorem}: The Life and Times},
booktitle = {Topology Atlas},
publisher = {York University, Toronto, Ontario, Canada},
year = 1996,
note = {\url{http://at.yorku.ca/topology/preprint.htm} and
\url{http://at.yorku.ca/p/a/a/a/16.htm}}
}
@Article{Nowak:1993,
author = {B. Nowak and A. Trybulec},
title = {{Hahn-Banach} Theorem},
journal = {Journal of Formalized Mathematics},
year = {1993},
volume = {5},
institution = {University of Bialystok},
note = {\url{http://mizar.uwb.edu.pl/JFM/Vol5/hahnban.html}}
}