If you have a character who quotes someone or something (such as a book, a person's words, or a song), and you explicitly mention the source, can you use it without any further issues? I'm thinking of giving one of my characters a notebook filled with such quotes that he carries throughout his journey and possibly sharing them with those who accompany him. For instance: "Hope is the thing with feathers that perches the soul," he remarked. "Hope is like a bird?" "Perhaps," he replied with a smile. "That's a line from a poem by Emily Dickinson.
That question gets into copyright issues, and i would say is better answered by a lawyer. I know John Ringo often uses song references in his works, but it is typically song name by artist type references. I have no idea if his publisher had to deal with any copyright issues to do that in the story. Another option is to limit your quotes, to ones you know have had their copy rights expire or are public domain. Either way it will take a fair amount of research.
If a work is in the public domain, there's no worries. https://copyright.universityofcalifornia.edu/use/public-domain.html#:~:text=A%20work%20is%20generally%20considered,and%20can%20be%20quoted%20extensively. Emily Dickinson's work, for example, is in the public domain. Another way to word it: "Hope," he quoted Emily Dickinson, "is the thing with feathers that perches in the soul."
