Cita APA (7th ed.)
Stanley Gibbons Publications Ltd & Mackay, J. A. Philatelic Terms Illustrated.
Cita Chicago (17th ed.)
Stanley Gibbons Publications Ltd i James A. Mackay. Philatelic Terms Illustrated.
Cita MLA (9th ed.)
Stanley Gibbons Publications Ltd i James A. Mackay. Philatelic Terms Illustrated.
Atenció: Aquestes cites poden no estar 100% correctes.