There are two interesting articles in the Financial Times today:

Data shift to lift US economy 3% and US economy gets a Hollywood makeover

According to the first article,

The revision, equivalent to adding a country as big as Belgium to the estimated size of the world economy, will make the US one of the first adopters of a new international standard for GDP accounting.

which links to the 2008 SNA page.

The manual/handbook of the new SNA is available at the Unstats site.

It is also available in print for $150 or $75 (depending on where you live).

It is the book to learn national accounts and is better if read from the start rather than being used as a reference for one particular point.  When you read it patiently, you will realize how much of work and effort has gone into it – especially to make the conceptual framework self-consistent.