History of the Peloponnesian War
Thucydides
Thucydides. The history of the Peloponnesian War, Volume 1-2. Dale, Henry, translator. London: Heinemann and Henry G. Bohn, 1851-1852.
So that for many reasons it happened that they returned quicker than usual, and that this was the shortest incursion they had made; for they remained in Attica but fifteen days.