Complex sentence: The series of prints were made by twenty-one-year-old Klinger in 1877-78 and first exhibited at the Berlin Art Association in 1878 then later exhibited in a mixed technique of engraving, etching, and aquatint in 1881.
Split into simpler sentences: The series of prints were made by twenty-one-year-old Klinger in 1877-78 and first exhibited at the Berlin Art Association in 1878. Then later exhibited in a mixed technique of engraving, etching, and aquatint in 1881.