What has the author A C Nielsen written?

There's no author known as "A C Nielsen." The name you're likely thinking of is Nielsen, which is a company, not an individual author.

Nielsen is a global information and measurement company, known for its television ratings and market research. They don't produce written content in the traditional sense of books or articles, but they do generate a lot of research data and reports on various topics.

If you are interested in finding out more about Nielsen's work, you can visit their website: [https://www.nielsen.com/](https://www.nielsen.com/)