| Catalogue | Country of Origin | Key Features | |-----------|------------------|---------------| | | Germany | Extremely detailed; strong on Europe, especially Germany & colonies; leading for expert collectors. | | Scott | USA | Most widely used in North America; accessible pricing; published as a multi-volume set updated annually. | | Yvert & Tellier | France | Specialized in French‑speaking countries & former French colonies; often the reference for classic issues. | | Stanley Gibbons | United Kingdom | The authoritative source for Commonwealth & Great Britain; higher “real market” price levels. |