Robert W. Chambers's Artwork for The King in Yellow

I've long understood that some of the artwork that appears on various covers of editions (but not the first printing) of The King in Yellow (1895) by Robert W. Chambers, was believed to be based on artwork by Chambers himself.  At last the evidence has emerged!  It comes in the form of original artwork by Chambers for a publicity poster from 1895, from the estate of Forrest J. Ackerman.  A truly