Langhe subregions

So as I am studying the crus of Barolo and Barbaresco, I am finding a good amount of vineyard names that are found within the different crus listed on bottles, but very little resources to which crus exactly. For example,  Ratti's "Marcenasco" Barolo is located in La Morra, but it is not listed as a cru. I know it is located near the town of Annunziata, but I want to know which cru it is a sub zone of, there are several options (Annunziata, Conca, Giachini or Rocche dell'Annunziata). And is their a source to find our all or at least the important sub zones?