I know what plagiarism is, but I was looking at the rules for a contest that said "Plagiarism, which includes the use of third-party poetry, song lyrics, characters or another person's universe, without written permission will result in disqualification." I'm writing a ST where one of my characters likes the book Of Mice and Men, and he compares his feelings to George. I assume that doesn't count as plagiarism, as I'm not developing the characters as if they are my own, I am simply alluding to a book that is very real and the characters within said book. Is this correct? Or is mentioning another author's books/characters not okay?