Nancy Bush writes in Sock Knitting Master Class:

“My inspiration for this sock design was a pair of socks
from Estonia. The original socks were knitted by my
friend Maimu Poldoja in a natural white wool yarn.
I studied the cables and spent some time making samples
to discover how they were worked so that the ribbing
melted into the stockinettestitch cables and then emerged
from the other side. I found that by making the cables a bit
“unbalanced,” each of the 7 rib stitches found a place in the
cable. I chose my favorite caston—the double-start method—
to provide a decorative and very elastic edge.”

--Copyright, Interweave Press 2011