Click on the links below to view key source documents.
July 25th Call Transcript — Trump and Zelensky
The Whistleblower Complaint
The ICIG’s Accompanying Letter to the Complaint
The DOJ OLC Memorandum Opinion
The ICIG’s 9 September Letter to Schiff and Nunes
The ICIG’s 17 September Letter to Schiff and Nunes
The ICIG”s 30 September Statement Regarding “Hearsay”
October 3 Release of Text Messages From Kurt Volker’s Phone
October 3 Volker Opening Statement Before Congress
October 8 White House Letter of Non-Compliance
October 11 Opening Statement of Ambassador Marie Yovanovitch
Additionally, here is a link put up by CNN on October 14 containing links to the documents above, plus a few others.