Thank you for the welcome.
The books that I used for the information of that article are in Dutch. I do not know if there are English translations availible (yet).
My English is far from perfect, but I hope the other group-members will ignore the occasional (spelling-)errors.

Those books are written by 2 authors. One of them is an historian and the other one is teaches Classical languages.
The 1st book was so much a success, that the authors wrote two others.
They analyse very much classical sources and give an explantation with it.

Authors : R. van Royen and S. van der Vegt

This book (is the 3rd of the series)
title book: De erfenis van Asterix: het leven in de lage landen.
book-number: 9035124340.

The title may be translated as: The inheritance of Asterix: life in the Low Countries.
The title is a reference to the comicbooks of the Gauls "Asterix and Obelix"