Previous to the execution of any official act of the President the Constitution requires an oathofoffice. This oath I am now about to take, and in your presence:
Coolidge's OathofOffice”. The New York Times. (1981年11月4日). https://www.nytimes.com/1981/11/04/obituaries/joseph-fountain-82-witness-to-coolidge-s-oath-of-office