• First check IUCAT to see if any IU library has a copy of the book. Don't rule out ebook copies; many ebooks are now PDF copies that have the same pagination as the print book.
• Next, check Google Books, Amazon, Internet Archive, and Hathitrust. Some publishers allow limited previews of recent books, and the older books have often been scanned by libraries. The books most difficult to find tend to have been published between 1923 and 1990. These books are still under copyright but weren't marketed online very much. 
• Finally, check WorldCat to see if there are any nearby libraries that have a copy. The library may be able to borrow a copy or obtain a scan or photocopy.

Law journal articles are relatively easy to obtain. Your first stop will be HeinOnline, which has comprehensive archives of most law journals. HeinOnline is a few months behind the newest journal issues. Journals often post their newest articles on their own websites.

A number of these journal websites are linked together through the Digital Commons Network, so it is worthwhile to search by title or author.

The Social Science Research Network (SSRN) is a database to which many law professors add their articles. SSRN is a great source for papers, especially drafts that have yet been formally published in a journal.

Of course, the library also has an extensive print collection of journals. These journals can be located through IUCAT.

Newspapers can be especially tricky sources to verify because news stories tend to disappear or move behind paywalls, and libraries generally discard print copies after a short time.

This challenge becomes very difficult if images of the paper issue are needed. ProQuest Digital Microfilm and ProQuest Historical Newspapers: The New York Times provide such copies for major papers like The New York Times and Indianapolis Star.

If the article you need isn't found in those databases, then ProQuest Newstand, Westlaw and LexisNexis are excellent news sources. The disadvantage of these sources is that the text is reformatted, most images are removed, and sometimes pagination is removed. While these copies may not be ideal in all respects, the substantive claims of the cited source can still be verified.

When verifying sources cited in articles, you want to find trustworthy copies of the sources. Librarians can help you find cited sources within the library's collection and licensed resources. If a source cannot be found in readily accessible places, the library can obtain many sources through interlibrary loan.

If you are spending more than 20 minutes searching for a source, then you can probably save time by asking a librarian for assistance.

International and foreign legal materials can be challenging to find. The first question you should ask is what authority published the document. Once you know the issuing organization, it will be easier to focus your search.

The United Nations and European Union have extensive online collections of their documents. Both organizations use an esoteric document numbering system, so be sure to pay attention to document numbers. UN documents can be found in the UN Document Sytem, while EU legal materials are at EUR-Lex.

Three excellent resources for finding international and foreign materials are the Electronic Information System for International Law, GlobaLex, and the Law Library of Congress's Guide to Law Online.

Of course, many nation states and international organizations have websites that are worth checking.

When searching for treaties, two important questions will help determine where to look. First, is the United States a party to the treaty? Second, is the treaty multilateral (involving more than two parties) or bilateral (between two parties)?

If the United States is or was a party to the treaty, there are a number of sources you can check.

• The State Department's Treaty Affairs office has a good collection of recent treaties in the Treaties in Force and the Treaties and Other International Acts Series.
• For older treaties, HeinOnline's Treaties and Agreements Library is an excellent collection. It has all the publication of the Treaty Affairs office, as well as other collections of treaties.

If the United States was not a party, then the United Nations Treaty Collection is a good place to start. Most countries file their treaties with the United Nations.