Landau invariably show work that would be welcome in any major art museum in the world. These two pieces are no exception.
Dubuffet was an artist whose work was the sharp stick aimed at the eye of the art world and the prevailing notions of what made art in his day. He was fascinated by the art of children and the art of mental patients. He also did not begin his art career until he was in his 40s. The MOMA website is a great place to begin finding out more about him.
Ernst was a German artist who exhibited in his homeland even while performing military service in World War I. Following the war he relocated to Paris. He was active in Surrealist circles (working with Andre Breton, among others). He also collaborated with Joan Miro and worked with Salvador Dalí and Luis Buñuel on the film, L'Age d'or. During World War II the Nazis included his work in a show they entitled "Degenerate Art." Hard to imagine a higher compliment to an artist to have offended the Nazi regime.
Start your internet rabbit hole at the Guggenheim website.