'well-referenced' is a compound formed from 'well' (Old English 'wel', meaning 'well' or 'properly') + the past participle 'referenced' derived from 'reference', which ultimately comes from Latin 'referre' where 're-' meant 'again' and 'ferre' meant 'to carry'.

'reference' came into English via Old French and Middle English (e.g. Old French 'referer', Middle English 'referren'), evolving from Latin 'referre' to the modern English 'reference'; 'referenced' is the past participle form used in compounds like 'well-referenced'.

Originally tied to the literal sense 'to carry back' (Latin), the root's meaning shifted over time toward 'to relate' or 'to direct to a source'; in modern English 'reference' and derived forms primarily mean 'a mention of a source' or 'citation', so 'well-referenced' now means 'having many/strong citations'.