S. Doc. 117-2: Proceedings of the United States Senate in the Impeachment Trial of Donald John Trump: Part I, February 2, 2021 [open pdf - 4MB]
This Senate document outlines Part I of the impeachment proceedings against Donald J. Trump, which includes:  Precept;  Writ of Summons;  Return of Service;  Answer of Donald John Trump to Article of Impeachment; and  Trial Memorandum of Untied States House of Representatives.
S. Doc. 117-2; Senate Document 117-2
U.S. Government Publishing Office: http://www.gpo.gov/