I'd love to try and integrate Dylan Thomas' poem, 'Do Not Go Gentle into that Good Night,' but I'm not sure what the copyright rules for poetry are. I did a little digging and it looks like it's copyrighted and not available for the public domain, but I also know the movie Interstellar was able to quote the entirety of the poem. Question 1.) Would I have to pay in order to use it in my novel, and Question 2.) If I WOULD have to pay, then could I possibly get by with just using a single line from the poem?