  We classify homomorphisms of the Baumslag-Gersten group into itself. We prove
it is Hopfian and co-Hopfian. We show that the group of outer automorphisms of
the Baumslag-Gersten group is isomorphic to the dyadic rationals with the
addition operation. These results are not new. They were obtained by Andrew M.
Brunner in \cite{Brunner}. However, our exposition is self-contained and,
hopefully, more accessible for some readers.
