Francisco Tropa, Putting creative people together, 2011, Painted wood, string. Francisco Tropa, Panta Rhei, 2016, silkscreen screen print, silk screen rearangeable cut-out elements, wooden frame, glass. Franz Erhard Walther. Rahmenzeichnung, 3 pieces, 1963, Pencil on paper. Versuch, eine Skulptur zu sein, 1958 / print 2010, Inkjet print on photo paper, black and white. Schraffurzeichnung, 1959, Graphite on paper. Materialbild Gelb, 1960, Cardboard, mousseline, paste, paint. Printemps, Eté, Automne, Hiver, Wortzeichnungen series, 1957/58, Pencil on paper. From Sternenstaub n°16, drawing in my studio, Düsseldorf, Talstrasse 69, 1964, 2011, Pencil on paper. Ph. Roberto Ruiz