Complex sentence: Pieter Goos was the first known person to map Christmas Island, which he labelled "Mony" in his "De Zee-Atlas ofte Water-Weereld" (1666), which has been cited as one of the best sea atlases of its time.
Split into simpler sentences: Pieter Goos was the first known person to map Christmas Island, which he labelled "Mony". His "De Zee-Atlas ofte Water-Weereld" (1666) has been cited as one of the best sea atlases of its time.