I need a book recommendation for Lie Groups/Group Theory. I am taking a QFT course and the first month is a whirlwind intro to Group Theory with an emphasis on Lie Groups. There is no book, but only the professors notes that doesn't give any proofs. His notes simply states a bunch of theorems, then goes on to give only very trivial examples. So, I was wondering if anyone knows of any books that are especially good on the subject? They should be accessable to someone who has never seen the material before. Thanks for any help you can give.