Claim: The Abell catalogue includes the Northern Survey and the Western Survey.
Evidence: This catalog supplements a revision of George O. Abell's original "Northern Survey" of 1958, which had only 2,712 clusters, with a further 1,361 clusters – the "Southern Survey" of 1989, published after Abell's death by co-authors Harold G. Corwin and Ronald P. Olowin from those parts of the south celestial hemisphere that had been omitted from the earlier survey.