Searching the "Visible" Web: The best free tools for plagiarism detection are Internet search engines. They allow you to search exact phrases or even whole sentences. If you suspect a paper has plagiarized text, choose some suspect phrases and copy them in a search engine. The engine will return all Internet documents in which the phrase appears AND which were indexed in its database. Among the many search engines currently available, the following are particularly efficient: Google, Yahoo, AlltheWeb, AltaVista and Gigablast. There are also Meta Search Engines like Dogpile, Mamma and MetaCrawler.

Points to remember when using search engines:

• No search engine covers all Internet pages. Thus, you should try the same key words or phrases in several search engines, or use meta search engines, which search several engines at a time, as is the case for MetaCrawler and Dogpile, both of which retrieve results from Google, Yahoo, and AltaVista. The meta search engine Mamma allows the selection of search sources and preferences


• The information contained in Portable Document Format (PDF) files is not accessed by many search engines. It is true that PDF files are harder to plagiarze since they cannot be incorporated into the student's paper. However, you should not ignore them because they are a very popular Internet file type


• Google, AlltheWeb, and Gigablast locate PDF, Word, Excel, and other file formats in addition to HTML files. AlltheWeb also indexes Macromedia Flash files

Not all Internet material is accessible through Internet search engines. Some websites are not indexed by search engines and can thus only be accessed through specific tools or directories. The following are some papers about the invisible web:

• In Those Dark Hiding Places: The Invisible Web Revealed! Robert Lackie provides links and information on specific search tools including directories, searchable sites and databases, and specialized search engines. Only a few of these tools are mentioned above; take a look at Lackie's page for many others
  http://www.robertlackie.com/invisible/index.html

• The Librarians' Index to the Internet "is a searchable, annotated subject directory of more than 12,000 Internet resources selected and evaluated by librarians for their usefulness to users of public libraries. lii.org is used by both librarians and the general public as a reliable and efficient guide to Internet resources..." http://lii.org/


• Infomine "is a virtual library of Internet resources relevant to faculty, students, and research staff at the university level. It contains useful Internet resources such as databases, electronic journals, electronic books, bulletin boards, mailing lists, online library card catalogs, articles, directories of researchers, and many other types of information." http://infomine.ucr.edu/

Some websites and some online bookstores offer book reviews--from the editor, from the critics, or from the readers. Here are some of them:

• Barnes & Noble: http://www.barnesandnoble.com/
• Amazon.com: http://www.amazon.com/
• Half.com: http://half.ebay.com/
• H-Net Reviews: "H-Net Reviews in the Humanities and Social Sciences is an online scholarly review resource." http://www.h-net.org/reviews/
• Look Smart's Find Article (and book reviews) is user-friendly and allows one to "search and read 3.5 million articles from over 700 publications." http://www.findarticles.com/PI/index.jhtml

Thus, if you suspect plagiarism in a book review prepared by one of your students, compare the suspected review with those available on the above sites.

TIP: Instructors can create databases of reviews of books that they ask their students to review. This allows them to easily compare suspect reviews when needed. Such databases can include both reviews found on the web and reviews presented by students in previous semesters.

• http://www.britannica.com/ (includes various browse features)
• http://www.encyclopedia.com/ (searches various encyclopedias and almanacs)

Some of the same paper mills that students might use for plagiarism can be used by instructors to examine suspect papers. This is especially true of sites that offer free papers because Internet search engines can locate these sites. They do not have access, however, to the databases of the sites that sell papers. These require subscriptions and it would be impossible for an instructor to subscribe to all of them and check each one of them individually.

We suggest that, as a last resort, instructors search:

• The free sites of paper mills
• Some sites with closed databases but with accessible paper abstracts. These sites allow you to search by topic or by keyword. Compare the descriptions of the papers your search brings with the suspect paper

To see these sites, open Google or another search engine and type "term papers" or "free term papers".

TIP: To save time, open a search engine and type "research paper" and the topic of the student's paper. The sites retrieved will include the paper mills that have papers on the topic.

In many cases, the professor's own database of previous papers is a great plagiarism detection tool. For that, always require students to hand in both hard copies and electronic versions of their papers. Colleagues teaching the same type of course (and asking for the same type of assignments) can share a common and thus larger database to avoid the same paper being submitted to different instructors.

In addition to the above mentioned tools, there are web applications and software created for the purpose of analyzing students' submissions and detecting matching texts. Read more