Google Books Ngram Viewer

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

Ngrams not found: valentine 's day, [valentine 's day]
The Ngram Viewer is case sensitive. Check your capitalization!

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1800 - 1955 1956 - 1992 1993 1994 - 1999 2000 valentines day English

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