Korean self-studying help

Hi everyone!

I’m looking to self study Korean, but I’m honestly not sure what textbooks/websites would be helpful in that process. I’ve seen a lot of people discuss what helped them the most but I haven’t seen any clear answers yet. If anyone has any suggestions it would be very much appreciated!

Also I’m not sure if this is necessary but I want to study Korean because I’m interested in pursing a PhD in linguistics (focusing on Korean culture/ language). Learning Korean more formally is essential to my research and I want to make sure I’m studying the best material out there.

Thank you :)!