Cita APA (7a ed.)
Billings, R. R., Laurence, M., & Shelton, W. ". México: Postal issue of 1874-1883 (Hidalgo Heads).
Cita Chicago Style (17a ed.)
Billings, R. R., Michael Laurence, 与 W.E. "Bill" Shelton. México: Postal Issue of 1874-1883 (Hidalgo Heads).
Cita MLA (9a ed.)
Billings, R. R., et al. México: Postal Issue of 1874-1883 (Hidalgo Heads).
警告：这些引文格式不一定是100％准确.