Ῥήβας
Could not find Ῥήβαν in Logeion dictionaries.
Ῥήβαν Proper-name noun: masculine accusative singular of Ῥήβας
Ῥήβας — Rhebas R. (Pontus), Pleiades 521135
Ῥήβας, α (ὁ) Rhèbas (auj. Riva), fl. de Bithynie, DP. 794 ; A. Rh. 2, 349, 652.