www.galaxyzoo.org

Anchor text: Galaxy Zoo – citizen science galaxy classification project

Wikipedia: Galaxy

Wikipedia: Hubble sequence

Anchor text: GalaxyZoo.org

Wikipedia: Galaxy morphological classification

Anchor text: Galaxy Zoo

Wikipedia: Institute of Cosmology and Gravitation, University of Portsmouth

Anchor text: Galaxy classification project, harnessing the power of the internet and the human brain

Wikipedia: Outline of galaxies