History of the Peloponnesian War

Thucydides

Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.

These first came to Macedonia and found that the former thousand had just taken Therme and were besieging Pydna;

so they also took part in the siege of Pydna. But afterwards they concluded an agreement and an alliance with Perdiccas, being forced thereto by the situation of Potidaea and tie arrival of Aristeus, which compelled them to hasten, and then they withdrew from Macedonia.