Prior to a joint Congressional committee and its televised hearings, the Tower Report conducted a limited investigation and issued this report..
This report and more than two dozen appendix volumes was issued by the joint Congressional committee which conducted a far more extensive investigation of the sales of arms to Iran and the use of that money to fund the Nicaraguan Contras.
Other documents related to the Iran-Contra affair.
For more documents and resources related to the Iran-Contra affair and its subsequent investigations:
National Security Archive: The Iran-Contra Affair - the excellent National Security Archive at Georgetown University launched its groundbreaking work with a chronology of the affair, and has an extensive collection of detailed documents relating to it.
Understanding the Iran Contra Affairs - Brown University hosts a website devoted to information, documents, and other Iran-Contra resources.