  Today, several universal digital libraries exist such as Google Books,
Project Gutenberg, Internet Archive libraries, which possess texts from general
collections, and many other archives are available, concerning more specific
subjects. On the digitalized texts available from these libraries, we can
perform several analyses, from those typically used for time-series to those of
network theory. For what concerns time-series, an interesting tool provided by
Google Books exists, which can help us in bibliographical and reference
researches. This tool is the Ngram Viewer, based on yearly count of n-grams. As
we will show in this paper, although it seems suitable just for literary works,
it can be useful for scientific researches, not only for history of science,
but also for acquiring references often unknown to researchers.
