父母簽證 question

I've been in U.S. about 10 years. My parents have never came to visit me
here. They applied visa once 5 years ago, got rejected. Since then, they
refused to apply again. I've been trying to persuade them for 5 years,
finally, they are okay with trying.

I felt it was my fault last time. So, I want to try my very best this time
to prepare documents for them.

Can someone kindly provide a list of documents that needed for B2 visa
application?

Thanks in advance.