the best for self-learners
If you are a self-learner who plans to reach the advanced levels in Korean I recommend you get the Francis Park four-volume series. They cover all levels: basic, intermediate, and advanced. Many reviews of the book online imply that it is a difficult book to use, but I don't agree with this at all: the grammar is explained in a very reader-friendly way, there are many examples, alot of grammar drills to get a solid grip of the grammar, and reading practises in each chapter. The print itself is quite large too, so I feel that the author has taken many steps to make the book as user-friendly as possible. If you are a self-learner I honestly think that you are wasting your time looking for other books, you are unlikely to find a more complete set such as this, and so easily available.
