Here are some of the best reference books that I have found relating to finding legitimate Publishers to submit your work to.

Writer’s Market 2020: The Most Trusted Guide to Getting Published

Why I would recommend this book:- Want to get published and paid for your writing? Let Writer’s Market 2020 guide you through the process with thousands of publishing opportunities for writers, including listings for book publishers, consumer and trade magazines, contests and awards, and literary agents—as well as new playwriting and screenwriting sections. These listings feature contact and submission information to help writers get their work published.