|Picard Vol. 1 on Chevrons - a copy is for sale on eBay|
Chevron Beads from the West African Trade (Volume 1), by John & Ruth Picard, there is one for sale right now -
The book has 8 pages of color images and 8 pages of descriptions of the beads.
The Picards issued a longer chevron book after this initial one - Vol. VII, which includes Nueva Cadiz beads.