  It is unlikely that uniqueness theorem holds for stationary black holes in
higher dimensional spacetimes. However, we will examine the possibility that
the higher multipole moments classify vacuum solutions uniquely. Especially, we
compute the potentials associated with rotational Killing vectors and look at
the dependence on the total mass M and angular momentum J. Consequently, there
is a potential $\sigma$ which we cannot write down in terms of integer power of
M and J explicitly. This may be regarded as an evidence for the uniqueness
using multipole moments generated by $\sigma$.
