The coins have always Sulla or sula.
"Plutarch's Lives, Volume II"
Aubrey Stewart & George Long
At noon of the 18th, we were within a mile of an island called sula, and sent our skiff ashore to speak with the natives.
"A General History and Collection of Voyages and Travels, Vol. VIII."
Robert Kerr
391 Zuk al-Habbabah, or grain market of Al-Madinah, 391 sula, or Sawab, Jabal, near Al-Madinah, ii.
"Personal Narrative of a Pilgrimage to Al-Madinah & Meccah"
Sir Richard Francis Burton