Another dissertation with relevance to Galatia has been published online. An abstract and link to download it in pdf is available here. This dissertation is in no way biblical and has limited usefulness to Galatians’ studies but is still of interest. Campbell argues that the invasion of Celts and Gauls had a very limited impact and concludes “that the establishment of Galatia as a geopolitical entity was probably unrelated to these incursive activities as traditionally indicated by the primary sources.” His supervisor was Graham Shipley.
Campbell, Duncan Robert John. The so-called Galatae, Celts, and Gauls in the Early Hellenistic Balkans and the Attack on Delphi in 280–279 BC. PhD; University of Leicester, 2009.