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.
On the return of the Peloponnesians from Attica, the Spartans themselves and the Perioeci who were in the neighbourhood of Pylos at once came to its relief; but the other Lacedaemonians were slower in coming, since they had just got back from another campaign.