Trust no one.
Information is available in all sorts of manifestations and formats, both paper and electronic.
Some information is more reliable than others. When you are finding information for a research paper, a project, or just to answer a question for yourself, you want to be able to determine the validity of the information you find. Print materials that you find in libraries have already been evaluated to some extent, since a librarian has chosen them for the collection. You must still determine, however, if the information is what YOU need. Not all print materials are reliable, however.