Clean up needed 

The list lacks of many Dukes, specially the first Frankish ones and those that were also Dukes of Aquitaine. Some linked Dukes's dates and correlations are somewhat confuse and inconsistent with each other. 

For those who can read Spanish, a complementary source may be Auñamendi Encyclopedia corresponding entry but it is a historical article not specifically focused in the Dukes but the Duchy and ending with the transformation of Vasconia into Gascony after Arnold's death. 

I have just written the corresponding entry Duchy of Vasconia, based on it and, when checking, I found some incongruencies, specially with Counts of Vasconia (a separate realm) listed as Dukes and some dates.