Washington, D.C. :
a Smithsonian book of the nation's capital.

APA Citation

Smithsonian Institution. (1992). Washington, D.C.: a Smithsonian book of the nation's capital. Washington, D.C.: Smithsonian Press.

MLA Citation

Smithsonian Institution. Washington, D.C.: a Smithsonian Book of the Nation's Capital. Washington, D.C.: Smithsonian Press, 1992.

Warning: These citations may not always be complete (especially for serials).