Citation, Documentation of Sources

Q. In a self-published novel, do you need the permission of a certain company to mention a product name/brand or other trademarked title?

A. You don’t need permission. Fortunately, we are all free to speak and write about Porsches and Jimmy Choos whether or not we can afford to buy them.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]