APA Format
Walker, Diana (Diana H.). (2007).
The Bigger picture : 30 years of portraits / by Diana Walker
. Washington, D.C. :: National Geographic,.
MLA Format
Walker, Diana (Diana H.).
The Bigger picture : 30 years of portraits / by Diana Walker
. Washington, D.C. :: National Geographic,, 2007
Chicago Format
Walker, Diana (Diana H.). The Bigger picture : 30 years of portraits / by Diana Walker. Washington, D.C. :: National Geographic,, 2007.