Sometimes professors say you can't use Web sources for your papers. Talk to your professor to clarify this, because there are basically two Webs.
When many people say the word Web they mean the Public Web. Anyone connected to the Internet can view this part of the Web. Most search engines only scan the Public Web.
The part of the Web you might not be familiar with is the Library Web. Since most search engines don't scan all Web pages, you could miss valuable information found in private databases. If you begin your search at the Beam Library's homepage, you can't go wrong. Besides, most professors expect students to begin searching for scholarly sources by using library databases on the Library Web.