OK! I'll try to explain....

I want to give an example of relevant literature for something. So I am writing "Subject X has been studied a lot internationally (e.g. Smith 2000, 2001, 2003 in the UK, Snow 2012 in Australia and Red 2012 in the US)"

Is this correct( I am refering to the references in the parenthesis) or I should put each date in a separate parenthesis?

(Does that make any sense????)
(Sorry I am not a native speaker of English) :)

I would write "Subject X has been studied a lot internationally: in the UK (Smith 2000, 2001, 2003), in Australia (Snow, 2012) and in the US (Red, 2012). But I don't think it matters too much.

Thank you!