Producers-Certified Level

As I'm doing my independent study for the Certified exam, I'm finding I'm gaining traction on blind tasting and the general theory for different regions. The area I'm finding a blind spot in is producers of classic regions. I have 1st growths of Bordeaux locked down and even 2nd and 3rd but have 0 point of reference for Germany(besides Dr. Loosen) , Italy, Chile, Argentina, Portugal, South Africa etc.. AVAs are easier to find and relate to, but I'm struggling with old world producers.

Any resources to highlight these areas? 

Thanks in advance.