Google Books Ngram Viewer

Graph these comma-separated phrases:
case-insensitive
between and from the corpus with smoothing of .  
Search in Google Books:

1950 - 1973 1974 - 1981 1982 1983 - 1984 1985 global cooling English
1950 - 1970 1971 - 1982 1983 1984 1985 global warming English

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