Joseph Beuys, Ja, Ja, Ja, Ja, Nee, Nee, Nee, Nee, 1969. Ed. 97/100. Quadrati di feltro e nastro registrato, 16,51 x 24,77 x 24,77 cm. Collection SFMOMA, The Panza Collection. Purchase, by exchange, through the bequest of J.D. Zellerbach and gifts of Mrs. Charles DeYoung Elkus, Mr. and Mrs. William C. Janss, Mr. and Mrs. Alfred Jaretzki, Jr., Harriet Lane Levy, and anonymous donors, and Accessions Commitee Fund, 2010. © 2018, ProLitteris, Zurich. Photo Alessandro Zambianchi, Milano