Canonical structural spine
The work's own structure
Reviewed edition: Isidori Hispalensis episcopi Etymologiarum sive Originum libri XX, ed. W. M. Lindsay, Oxford: Clarendon Press, 1911, volumes I–II. Division axes: book → chapter → section. Structural nodes alone do not assert commentary citations.
Record-local commentary evidence
Commentary citations: work locus ↔ Dante locus
These citations occur in later commentary. They do not, by themselves, mean Dante cited this work.