  Experimental results of the $^{237}$Np($d, p \gamma)^{238}$Np reaction are
presented, which verifies the generalized Brink-Axel (gBA) hypothesis for
$\gamma$ transitions between states in the quasi-continuum. The gBA hypothesis
holds not only for specific collective resonances, but for the full dipole
strength below the neutron separation energy. We discuss the validity of the
gBA hypothesis also for lighter systems like $^{92}$Zr where the concept of a
unique $\gamma$-ray strength function ($\gamma$SF) is problematic due to large
Porter-Thomas fluctuations. Methods for studying the $\gamma$SF and the
fluctuations as function of excitation energy are presented.
