Google Books Ngram Viewer

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

1800 - 1941 1942 - 1962 1963 - 1965 1966 - 1988 1989 - 2000 noctilucent clouds English
1800 - 1947 1948 - 1973 1974 - 1976 1977 - 2000 2001 - 2000 noctilucent cloud English

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