Authors:

In the discharge of duties my guide will be the Constitution, which I this day swear to preserve, protect, and defend.

John J. Farrell, Zachary Taylor, United States. President (1849-1850 : Taylor), United States. President (1850-1853 : Fillmore) (1971). “Zachary Taylor 1784-1850 [and] Millard Fillmore 1800-1874: chronology, documents, bibliographical aids”, Oceana Pubns
In the discharge of duties my guide will be the Constitution, which I this day swear to preserve, protect, and defend.