endgame books/studying for 1300

In terms of time and accessibility chess courses are generally better to learn from than chess books. Chess books are hard to follow, you need to setup a board and meticulously move the pieces while looking between the book / board, it takes quite a while. I wouldn't recommend it unless it's a real classic or you're higher rated and looking to achieve mastery. The amount of information and ease of which you can get it is just much greater with a course. My suggestion would be to find some chessable or chessbase course on the endgame, purchase it, and vuala.