Lua APA (7ú heag.)
Billings, R. R., Laurence, M., & Shelton, W. ". México: Postal issue of 1874-1883 (Hidalgo Heads).
Lua i Stíl Chicago (17ú heag.)
Billings, R. R., Michael Laurence, agus W.E. "Bill" Shelton. México: Postal Issue of 1874-1883 (Hidalgo Heads).
Lua MLA (9ú heag.)
Billings, R. R., et al. México: Postal Issue of 1874-1883 (Hidalgo Heads).
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.