The citations this atlas's facts are drawn from: encyclopedia entries, academic journals, government archives, institutional and university official pages, open courseware and the other material a fact or a quote traces back to. Every specific claim in this atlas is expected to carry a source that actually states it, per this atlas's own write time discipline; a source entity is the record of where that support came from, carrying its own locator and, where captured, a short verbatim supporting quotation. This category's own internal classification, what kind of source each citation is, is a live gap this wave found and left for a successor rather than a designed scheme.