I've already provided that resource, Nickel.
View all 9 volumes on Google, searchable in Greek here:
Earion dear, I looked up that tribe's name (Αττεκότιοι), but no luck.
Try again using different spellings (Ατεγούτοι?)
Meantime, there's lots on the Cottian Alps, under the entry ΑΛΠΕΙΣ...