The Text
There shall be for each State of the Federation a Governor. The Governor of a State shall be the Chief Executive of that State.
Source · Constitution of the Federal Republic of Nigeria, 1999, as amended · §176
All sections in Chapter VI — The Executive
Methodology
Tier 1 · primary
Courts. Gazettes. National archives.
Tier 2 · corroborating
OCCRP. HRW. BudgIT. TheCable.
Redline
Wikipedia is never a source.