A vertex set $D$ in a finite undirected graph $G$ is an {em efficient dominating set} (emph{e.d.s.} for short) of $G$ if every vertex of $G$ is dominated by exactly one vertex of $D$. The emph{Efficient Domination} (ED) problem, which asks for the ex
istence of an e.d.s. in $G$, is known to be NP-complete for $P_7$-free graphs, and even for very restricted $H$-free bipartite graph classes such as for $K_{1,4}$-free bipartite graphs as well as for $C_4$-free bipartite graphs while it is solvable in polynomial time for $P_8$-free bipartite graphs as well as for $S_{1,3,3}$-free bipartite graphs and for $S_{1,1,5}$-free bipartite graphs. Here we show that ED can be solved in polynomial time for $(P_9,S_{1,1,6},S_{1,2,5})$-free chordal bipartite graphs.
