Strabo Geography 9.2.19

[19] Now these rivers flow down from the Phocian mountains, and among them the Cephissus, which takes its beginning at Lilaea, a Phocian city, as Homer says: “And those who held Lilaea, at the sources of Cephissus.” ¹ And flowing through Elateia, the largest of the cities of Phocis, and through Parapotamii and Phanoteus, ² which are likewise Phocian towns, it goes on into Chaeroneia in Boeotia, and then through the territories of Orchomenus and Coroneia, and discharges into Lake Copais. And also the Permessus and the Olmeius, flowing from Helicon, meet one another and fall into the same Lake Copais near Haliartus; and also other streams empty into it. Now it is a large lake, having a circuit of three hundred and eighty stadia, but its outlets are nowhere to be seen, except for the fissure which admits the Cephissus, and for the marshes.

[19] These rivers descend from the Phocian mountains, and among them the Cephissus, ¹ having its source at Lilaea, a Phocian city, as Homer describes it;

And they who occupied Lilaea, at the sources of Cephissus. ²

Il. ii. 523. It flows through Elateia, ³ the largest of the cities among the Phocians, through the Parapotamii, and the Phanoteis, which are also Phocian towns; it then goes onwards to Chaeroneia in Boeotia; afterwards, it traverses the districts of Orchomenus and Coroneia, and discharges its waters into the lake Copais. The Permessus and the Olmeius ⁴ descend from Helicon, and uniting their streams, fall into the lake Copais near Haliartus. The waters of other streams likewise discharge themselves into it. It is a large lake with a circuit of 380 stadia; ⁵ the outlets are nowhere visible, if we except the chasm which receives the Cephissus, and the marshes.