The book that I recommend the most is [Korean Grammar for International Learners][1]. This book is published by Yonsei University and I feel is very high quality. I have used this book for about 8 years now. It has served me well as I have progressed from beginner clear through a college degree in Korean. This book does an excellent job at helping you no matter what level your Korean is at. I have seen a lot of Korean grammar books, and this is one of the top choices in my opinion. 

Another book that is useful for beginners learning grammar is [500 Basic Korean Verbs][2]. This book (as the title suggests) has 500 of the most used verbs in Korean. It walks you through how to conjugate the verbs in all sorts of tenses and forms. I found this book to be pretty useful, especially with irregular verbs. 


  [1]: https://www.amazon.com/Korean-Grammar-International-Learners-Bin/dp/8971415541
  [2]: https://www.amazon.com/500-Basic-Korean-Verbs-Comprehensive/dp/0804842051