By History of English, Present perfect

Thank you for the kind proposal. If you have the titles of those books, could you kindly put them in the thread of the history of English language in Linguistics Discussion Forum? I'm interested especially in the language change happened during/immediately after the Viking Age. paco

I got this kind of knowledge through OED and a cheap book written by late Toshio Nakao who was a lecturer on history of English in some university (University of Glasgow?) in Great Britain. paco