I started thinking about the usage of the Oxford comma and it seemed that Google's Ngram Viewer is the ideal tool for the job. Unfortunately, commas are a meta characters in the search language:
Why am I not seeing the results I expect?
- Your phrase has a comma, plus sign, hyphen, asterisk, colon, or forward slash in it. Those have special meanings to the Ngram Viewer; see Advanced Usage. Try enclosing the phrase in square brackets (although this won't help with commas).
Sure enough, square brackets don't help with commas.
However, it should be possible to search for literal asterisks. Unfortunately, the specific ngram you are looking for seems not be in the data. It's hard to know if there is yet another syntax problem in my search or if that particular string has not been found in books. The later seems unlikely.
It may be necessary to download the dataset.