Broecker (1975)
Also: Broecker 1975
Climatic change: are we on the brink of a pronounced global warming?
Broecker, W. S. (1975). Climatic change: are we on the brink of a pronounced global warming. Science; (United States), 189(4201). Link to book chapter
References
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.