Where can I find the interpretations about NBA official rules (without going to a camp), books or websites?

Personally I think NBA official rules are not as detailed and clarified as NCAA, FIBA etc. The interpretations, if they exist, are not readily available either.

Thanks.

On their website.

I have reffed using NBA rules now for many years. I believe that in many circumstances the NBA rules are more clear and any in many ways more concise than FED/NCAA.

Most of the time the rules that are not clear are because they are different tan what you are used to.

The NBA also has a casebook just like everybody else, it is not something sold on Amazon.com or BasketballRUS.com

Glad to find someone who respects NBA rules. Lots of folks here do not seem to care a lot about NBA rules, probably because of the way it is enforced.

Do I have to go to a camp to get a casebook, or you know there are other places to get one? Thanks.

Not exactly, Ysong. We generally don't care about the NBA rules because we don't work them much. Most of us aren't big fans of the NBA, and that has nothing to do with the officiating.
Don't assume our apathy regarding the NBA is a reflection of our view of the officiating. Most of us recognize that the NBA refs are highly competent and highly qualified; we just don't care for the game.