Ask HN: What are some good dedicated textbooks on Graph Theory?

I am a fairly experienced Software Engineer with a computer science degree. During the graduation course, I did study Graph theory, but only as a part of Data Structure/Algorithms, and also that was ~10 years ago.

I would like to explore it further and in formal detail. I am assuming it must be a part of curriculum for Mathematics/Applied Mathematics? What are the recommended resources (preferably Textbooks)?