The Ngram Viewer will let you compare using numerous words or names in one graph. The example that I offer in this video is to compare using the terms “National Parks,” “National Forests,” and “National Forest Service.” By taking a look at the Ngram Viewer for those terms I can see that they begin to appear more regularly around 1890, have a lull in the 1940s and 1950s, and after that appear more regularly again in the 1960s..
Ngram Viewer is based upon books indexed in Google Books. That is why listed below every graph produced by Ngram Viewer you will find a list of books about each of your search terms. Those books are arranged by date..
A 3rd part of Ngram Viewer to note is that it works with several languages consisting of English, French, Chinese, German, Italian, Russian, Hebrew, and Spanish..

Ngram Viewer is a search tool that students can utilize to check out the use of words and names in books released in between 1800 and 2019. The Ngram Viewer reveals users a graph showing the very first look of a word or name in literature and the frequency with which that word or name appears in literature because 1800. The Ngram Viewer will let you compare the use of multiple words or names in one graph.

By the method, the book that I mentioned in the video is That Wild Country by Mark Kenyon..

Applications for Education.
As I discussed in the video above, the Ngram Viewer can offer a great way to start a research study activity for students. Have them enter a couple of words then analyze the graph to recognize peaks and valleys in the frequency of the words use. Ask them to attempt to identify what would have caused those words to be used more or less often at various durations in history.

Googles.
Ngram Viewer is a search tool that students can use to check out making use of words and names in books published between 1800 and 2019. The Ngram Viewer reveals users a chart illustrating the first look of a word or name in literature and the frequency with which that word or name appears in literature considering that 1800. The graph is based upon the books and regulars that are indexed in Google Books.