Citing the Commons
The OSID is the citation. Reference the identifier and the permanent resolver, and your citation outlives any redesign of this site.
The principle
Every record has one permanent identifier — its OSID — and one permanent address: the resolver. Both are commitments measured in decades. Cite those, rather than page URLs, screenshots, or catalog page numbers, and the reference stays good.
In a journal or catalog
A standard reference names the record, the OSID, and the resolver:
Inline, the OSID alone is sufficient once the source is established — set it in a monospace face where the medium allows, as this catalog does.
In software and data
Store the OSID string itself as the foreign key — it is the primary key of the catalog and will never change once assigned. For machine consumers, the API returns the canonical record as JSON:
Third parties may reference OSIDs freely but may not mint them: assignment authority rests exclusively with the OSC platform, which is what keeps the identifier space coherent.
Deprecated records
Deprecated OSIDs keep resolving for decades and point at their canonical successor. A citation to a deprecated record therefore still works; follow the resolver to the successor when precision matters. Never rewrite an old citation — the resolver does that work for you.
For the full catalog, cite "Open Stamp Commons (openstampcommons.org), CC0" with your retrieval date, or the dated bulk snapshot once snapshots publish.