As you can see, there is not a great deal of information on this particular subject. The following list is the result of poring through every book that I thought might possibly be useful and searching for pictures of the few pieces of embroidery that have survived.
Most of the available information concerns the woven pieces that were produced by the Copts. If you are interested in this subject, you might also seek out books on Coptic textiles—it will give you a feel for the design trends of the time. Most embroidered pieces utilize the same design elements as the woven pieces.
Johnstone, Pauline. The Byzantine Tradition in Church Embroidery. Chicago: Argonaut, 1967.
This book has some discussion of the stitches used in Coptic embroidery, as well as some speculative comments to when embroidered pieces used instead of woven.
Gostelow, Mary. A World of Embroidery. New York: Scribner, 1975. ISBN: 0684152509
This book has a picture of a piece of Coptic embroidery (for the complete picture, see Coptic Textiles in the Brooklyn Museum).
Rutschowscaya, Marie-Helene. Coptic Fabrics. Paris: Adam Biro, 1990. ISBN: 2876600846
This is an excellent resource. It contains pictures of two extant pieces of embroidery, as well as many woven Coptic pieces. There is also discussion of the embroideries and the stitches used.
Thompson, Deborah. Coptic Textiles in the Brooklyn Museum. Brooklyn Museum, 1971. ISBN: 0913696110
This book contains clear pictures and commentary on two embroidered pieces: a chainstitched piece, and two small roundels. An excellent resource!
Warner, Pamela. Embroidery: A History. London: Batsford, 1991.
This book includes a brief description of the Annunciation roundel, as well as some general information about Byzantine decoration.
(All copyright privledges remain with the author. Copyright 2002 Scorcha Valdimarsdottir)