N.P. N.p., n.d. (ca. 1968). Bifolium, approx. 6-1/2 X 8-1/2 in., printed on all sides. Vertically folded, as for mailing; small crease to one corner, very good. Item #206062
The beloved author and illustrator of Harold and the Purple Crayon and other classic books for children devoted his last years to making exacting mathematic paintings, most of which are in the collection of the Smithsonian Institution. This brochure includes both a verbal and mathematical explanation of its method.