"Op. 67" 1987 Copperplate engraving 12x16.5 cm "Op. 68" 1987 Copperplate engraving 12x16.5 cm "Op. 69" 1987 Copperplate engraving 16.5x12 cm "Op. 72" 1987 Copperplate engraving 13x10 cm "Op. 73" 1987 Copperplate engraving 12x16.5 cm