Without access to a library that subscribes to a Congressional documents database (or that has retained the print), you will have a devil of a time finding many Congressional documents, especially those before the 94th Congress (1975-76) or after 1865. (See the LOC Century of Lawmaking for a New Nation, the National Archives, or the GPO Congressional Documents database.)
You might want to try Congress dot gov, where you’ll find bills and resolutions and, hmmm – no reports.
Let’s say you want to find this document, which is a “report.”
U.S. House. Committee on the Judiciary. Impeachment of Richard M. Nixon, President of the United States: Report of the Committee on the Judiciary, House of Representatives, Peter W Rodino, Jr., Chairman. 93rd Cong., 2d Sess. August 20, 1974. Washington: U.S. GPO, 1974. 528 p. Includes bibliographical references.
Let’s say you can find that report’s numbers, which to save time I’ll give to you:
H.RPT. 93-1305; H.DOC. 93-339. CIS#: 74-H520-6; CIS#: 74-H523-11. SERIAL 13064-3. LCCN: 74603038. KF32.J8 1974
You have 3 options, at least, if you want to find the full text of the report:
1) Your library might have this book, which also includes the report: “Responses of the Presidents to charges of misconduct,” by C. Vann (Comer Vann) Woodward, 1908-1999. United States. Congress. House. Committee on the Judiciary. New York : Dell Pub. Co. 1974.
2) Find a library that will give you access to print or online U.S. Government documents. (Note: most colleges and universities will subscribe to the CIS database (see the CIS number above). Some very large public libraries may also subscribe to it.)
3) Visit this Hathitrust database record and look for Serial Set # 13064-3.
P.S. A new book is to be published (circa July 2019) that includes the above report and related documents:
“Presidential Misconduct from George Washington to Today,” James M. Banner, editor. It includes an introduction by (the late) C. Vann Woodward, whose research was reported on by Jill Lepore in an August 26, 2018, New Yorker magazine article: “Measuring Presidents’ Misdeeds.”
P.P.S. There are a zillion other books, government reports, and articles (in law and related disciplines) on impeachment and the U.S. Constitution. Have at it.