From A Second Treasury of Knitting Patterns by Barbara Walker, page 287. Before knowing about Stitch Maps I tried to chart this pattern, but found it difficult to handle the changing stitch count. So I made a rough "free-form" chart without vertical grid lines, realising that this could usefully also show the proper vertical alignment of the stitches (see photo). Later I wondered if somebody had thought of this before, and indeed they had. I'm so pleased to have discovered this site.
Shown with a cast-on count of 31 stitches.