Histories
Herodotus
Herodotus. Godley, Alfred Denis, translator. Cambridge, MA; London: Harvard University Press; William Heinemann, Ltd., 1920-1925 (printing).
Disputes arose over it, so the Spartans resolved to ask the oracle at Delphi [22.5167,38.4917] (Perseus) Delphi if Demaratus was the son of Ariston.
At Cleomenes' instigation this was revealed to the Pythia. He had won over a man of great influence among the Delphians, Cobon son of Aristophantus, and Cobon persuaded the priestess, Periallus, to say what Cleomenes wanted her to.