This free pattern originally published in:
Spool Cotton #58, The Learn How Book
This free pattern originally published in:
Spool Cotton #98, The Learn How Book 
Cast on a number of stitches divisible by four, then knit 2, purl 2 across. On next row, if last two stitches were purled, start the next row with knit 2, then purl 2 and continue across. Another ribbing is made by casting on an even number of stitches and knitting 1, purling 1.
other patterns in leaflet: