Arrian, Periplus Maris Euxini 31.
Dio Chrysostom, The Borysthenitic Discourse, 36.2.4.
Herodotus 4.18, 4.78-79.
Scymnus of Chios, Periegesis 804.
Strabo 7.3.17.
Ammianus Marcellinus, Rerum Gestarum Libri 22.8.
Plinius, Naturalis Historia 4.12.
Pomponius Mella, De Chorographia 2.6.