The Nisos reference article from the English Wikipedia on 24-Apr-2004
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Nisos

In Greek mythology, Nisos was one of the four sons of Pandion.

Upon the death of Pandion, Nisos and his brothers (Aegeas, Pallas, and Lykos) took control of Athens from Metion, who had seized the throne from Pandion. They divided the government in four but Aegeas became king.