Cita APA (7a ed.)

Cobban, W., & Kennedy, W. (1990). Observations on the Cenomanian (Upper Cretaceous) ammonite Calycoceras (Calycoceras) obrieni Young, 1957 from Arizona and New Mexico.

Cita Chicago Style (17a ed.)

Cobban, W., y W. Kennedy. Observations on the Cenomanian (Upper Cretaceous) Ammonite Calycoceras (Calycoceras) Obrieni Young, 1957 from Arizona and New Mexico. 1990.

Cita MLA (9a ed.)

Cobban, W., y W. Kennedy. Observations on the Cenomanian (Upper Cretaceous) Ammonite Calycoceras (Calycoceras) Obrieni Young, 1957 from Arizona and New Mexico. 1990.