Turnshoes

According to History of Shoes, by 1480 the first shoes made right-side out on a last (a mold) were developed in Germany and spread throughout Europe, or in other words, a turn shoe. From what I gather, most sources say that turn shoes didn't start until this time frame, so it makes me wonder about the shoe construction before 1480. This next link on Birka Traders makes me wonder at their construction of a shoe from an earlier period. Though this shoe isn't from the German Renaissance time frame, I figured since I was working on shoes at this time anyway, I'd include it in case I need an earlier time frame pattern later. This next site (Reproducting a Late 14th Century Shoe using Patterns Taken from Extant Examples[1]) is interesting, but the information seems to conflict with other information I've acquired so far. How old is the turn shoe method really? Here is another site on A Burgundian Court Shoe from the early 15th century that also claims the use of a last and turning the shoe inside out. I don't suppose it's overly important for German Renaissance reconstruction when the turn shoe started, considering they were available from everything I've seen so far to the German Renaissance individual, but this aspect bugs me when people can't agree on when a technique actually started.