Some texts are issued in multiple volumes which may be numbered (a multi-volume set, journals, etc.).If you consult a particular volume of the numbered set, include the volume.
Rampersad, Arnold. The Life of Langston Hughes. 2nd ed., vol. 2, Oxford UP, 2002.
Wellek, Rene. A History of Modern Criticism, 1750-1950. Vol. 5, Yale UP, 1986.
For periodicals, the number corresponds with the issue.
Baron, Naomi S. "Redefining Reading: The Impact of Digital Communication Media." PMLA., vol. 128, no.1,
Jan. 2013, pp. 193-200.
Kafka, Ben. "The Demon of Writing: Paperwork, Public Safety, and the Reign of Terror." Representations, no. 98,
2007, pp. 1-24.
Note: If a work in a periodical is not printed in consecutive pages, just list the start page number and a plus sign.
Clowes, Daniel. David Boring. Eightball, no. 19, Fantagraphics, 1998.
Seasons of a Television Series
"Hush." Buffy the Vampire Slayer, created by Joss Whedon, performance by Sarah Michelle Gellar, season 4, episode 10
Mutant Enemy, 1999.