APA
Held G. r., . (1996). Understanding data communications 5th ed. [Place of publication not identified]: Sams Publishing.
Chicago
Held Gilbert rev, . 1996. Understanding data communications 5th ed. [Place of publication not identified]: Sams Publishing.
Harvard
Held G. r., . (1996). Understanding data communications 5th ed. [Place of publication not identified]: Sams Publishing.
MLA
Held Gilbert rev, . Understanding data communications 5th ed. [Place of publication not identified]: Sams Publishing. 1996.