The full story is almost better than that. As told by his brother:

"Well, this old librarian, she says, 'This library is not for coloreds.' He said, 'Well, I would like to check out these books.'

"She says, 'Young man, if you don't leave this library right now, I'm gonna call the police.'

"So he just propped himself up on the counter, and sat there, and said, 'I'll wait.' "

[The police and his mother were called]

"And the police officer said, 'You know, why don't you just give the kid the books?'

"And my mother said, 'He'll take good care of them.' "

So, the librarian reluctantly handed over the books. And then, Carl says, "my mother said, 'What do you say?' "

And Ron answered, "Thank you, ma'am."

Full story: NPR