 Thereafter, he exhibited extensively in galleries and museums in the United States and Europe, as well as in international exhibitions such as documenta V (1972), and was included in many surveys of conceptual art.The last retrospective of his work during his lifetime was presented at the Palais des Beaux-Arts in Brussels in 1994.There have been several posthumous one-person exhibitions, including at the Camden Arts Centre, London (2002) and the MAMCO, Geneva (2006).