The student's Gibbon :
the history of the decline and fall of the Roman empire /
by Edward Gibbon ; abridged, incorporating the researches of recent commentators, by William Smith.

APA Citation

Gibbon, E., Smith, W. (1857). The student's Gibbon: the history of the decline and fall of the Roman empire. New York: Harper & Bros..

MLA Citation

Gibbon, Edward, 1737-1794, and William Smith. The Student's Gibbon: the History of the Decline And Fall of the Roman Empire. New York: Harper & Bros., 1857.

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