 "” In 1964, for the first time in forty years, Burkhardt returned to Basel, and began making annual summer visits where he became a friend of Mark Tobey—printing linocuts for the artist and collecting his work.In the 1970s Burkhardt continued his anti-war paintings—incorporating protruding wooden spikes into the canvas—while simultaneously painting abstractions of merging lovers and cityscapes during his summer visits to Basel.His “Small Print” (protesting smoking), “Graffiti,” and “Northridge” series demonstrate the evolution of his symbolism, and his “Desert Storms” series, in response to Iraq's invasion of Kuwait, was discussed by critic Peter Selz at a presentation at the International Congress of Art Critics Conference.