The Wychwood Warriors Wiki offers an article on the history and design of coats and overtunics for early Germanic cultures and Vikings. Included are resources, with links, for Eastern Viking and female coats.
From the article:
Most Saxons and Vikings wore the standard woollen overtunics that we all know and love, however this was not a universal style. This article will examine the evidence we have for four different styles of coats- the early Germanic “warrior jacket”, the two cuts of Eastern Viking riding coats and finally the female coat. Somewhat confusingly, all four of these styles are sometimes called kaftans.
Obviously kaftans aren’t appropriate for all Wychwood characters. The warrior jacket was primarily popular before our period; the two kaftans are distinctively Eastern so should probably be used to draw attention to particular ethnicities or as a sign of having travelled in the Rus lands; and the female coat may never have even existed.