Johann Sadeler I (1550-1600), Kalendrivm Perpetvvm (Gregorian perpetual calendar, with the Four Seasons), 1595, engraving on paper, 317 × 242 mm; Amsterdam, Rijksmuseum, RP-P-OB-7498. Photo: Rijksmuseum 
Public domain.
Rijks RP-P-OB-7498
Johann Sadeler I (1550-1600), Kalendrivm Perpetvvm (Gregorian perpetual calendar, with the Four Seasons), 1595, engraving on paper, 317 × 242 mm; Amsterdam, Rijksmuseum, RP-P-OB-7498. Photo: Rijksmuseum Public domain.