Linked from
The 28 pages that link to Galaxy, each with the reason it gives.
Hubble sequenceNarrower topic: The sequence sorts galaxies according to their observed forms.
Galactic bulgeNarrower topic: The bulge is one structural component within a galaxy.
Nuclear star clusterNarrower topic: The cluster is a compact component of its host galaxy.
Messier 81Narrower topic: M81 is one member of this wider class of cosmic systems.