Sidney Eileen's gorgeous seam treatment on a Viking linen apron dress. The thread on Facebook contains some other links to Viking-era embroidery patterns and techniques, some of which are quite lovely.
Pumora's Lexikon der Stickstiche: die Hexenleiter
In 1984 Inga Hagg published a book about some 9th and 10 th century finds at Hedeby (northern Germany). This book is written in a language that I do not understand (German), but it contains some diagrams which have proven very useful.
GWENT - Dol Blathanna Trapper, Bogna Gawrońska on ArtStation at https://www.artstation.com/artwork/wqzz5