As an academic, my papers (I assume) have been cited. But only once do I remember a publisher, on behalf of a writer, contacted me to ask if they could reused (or republish) a chart I had created in one of papers – for a textbook. I gave them my permission and that was the end of it.
Now I am about to publish my first (non academic) book. I still have footnotes with citations, maybe 5-10 per chapter, but it never occurred to me to ask permission, as long as the citation was proper. The only time I asked for permission was when I printed a comic strip by a popular author.
So – for the other citations – do I need to get permission to publish a quote, or a small excerpt? (for instance if a sentence with an industry fact or statistic).