As a student, you need to be able to identify different TYPES of sources in order to use them wisely.  One way is to consider how information travels through the information cycle:

Courtesy of the University of Illinois http://www.library.illinois.edu/ugl/howdoi/informationcycle.html

The Day of an Event

Television, The Internet, and Radio

The information:

• Is primarily provided through up-to-the-minute resources like broadcast news, Internet news sites, and news radio programs.
• Is quick, generally not detailed, and regularly updated.
• Explains the who, what, when, and where of an event.
• Can, on occassion, be inaccurate.
• Is written by authors who are primarily journalists.
• Is intended for a general audience.

The Day After an Event

Newspapers

The information:

• Is longer as newspaper articles begin to apply a chronology to an event and explain why the event occurred.
• Is more factual and provides a deeper investigation into the immediate context of events.
• Includes quotes from government officials and experts.
• May include statistics, photographs, and editorial coverage.
• Can include local perspectives on a story.
• Is written by authors who are primarily journalists.
• Is intended for a general audience.

The Week of or Weeks After an Event

Weekly Popular Magazines and News Magazines

The information:

• Is contained in long form stories. Weekly magazines begin to discuss the impact of an event on society, culture, and public policy.
• Includes detailed analysis of events, interviews, as well as opinions and analysis.
• Offers perspectives on an event from particular groups or geared towards specific audiences.
• While often factual, information can reflect the editorial bias of a publication.
• Is written by a range of authors, from professional journalists, to essayists, to commentary by scholars or experts in the field.
• Is intended for a general audience or specific nonprofessional groups.

Six Months to a Year After an Event and On...

Academic Journals

The information:

• Includes detailed analysis, empirical research reports, and learned commentary related to the event.
• Is often theoretical, carefully analyzing the impact of the event on society, culture, and public policy.
• Is peer-reviewed. This editorial process ensures high credibility and accuracy.
• Often narrow in topic.
• Written in a highly technical language.
• Includes detailed bibliographies.
• Is authored by scholars, researchers, and professionals, often with Ph.D's.
• Is intended for other scholars, researchers, professionals, and university students in the field.

A Year to Years After an Event and On...

Books

The information:

• Provides in-depth coverage of an event, often expanding and detailing themes, subjects, and analysis begun in academic research and published in journals.
• Often places an event into some sort of historical context.
• Can provide broad overviews of an event.
• Can range from scholarly in-depth analysis of a topic, to popular books which provide general discussions and are not as well-researched.
• Might have a bias or slant, but this dependent on the author.
• Includes bibliographies.
• Is often written by scholars, specialists, researchers, and professionals, though credentials of authors vary.
• Can be intended for a broad audience depending on the book, ranging from scholars to a general audience.

Government Reports

The information:

• Comes from all levels of government from state, federal, and international governments
• Includes reports compiled by governmental organizations and summaries of government-funded research
• Is factual, often including statistical analysis
• Often focuses on an event in relation to public policy and legislation
• Authored by governmental panels, organizations, and committees
• Is intended for all audiences.

Reference Material

The information:

• Is considered established knowledge.
• Is published years after an event takes place, in encyclopedias, dictionaries, textbooks, and handbooks.
• Includes factual information, often in the form of overviews and summaries of an event.
• May include statistics and bibliographies.
• Often not as detailed as books or journal articles.
• Authored by scholars and specialists.
• Often intended for a general audience, but may be of use to researchers, scholars or professionals
  
  Courtesy of the University of Illinois http://www.library.illinois.edu/ugl/howdoi/informationcycle.html

1) Easy, paid for, access to publications you can't find on the "open web" and would be quite expensive to access. Take the Economist, for example. Unless you have your own subscription, you can only read a few articles via the Economist website each month. But if you belong to a library that pays for a subscription to the ABI/INFORM articles database, you can read current and back issues of the Economist at no cost to you.

2) You can limit results with advanced searching to

• when they were written
• who wrote them
• type of materials, such as those that have gone through an important quality-control process called peer review

3) Results are more likely to be reliable. Information included in subscription databases is vetted, meaning that qualified people make decisions about which publications should be added to them. This editorial oversight reduces the advertisements and other junk that can dominate the early pages of your Google results sets. There are no guarantees, but the information you find when searching in subscription databases tends to be fairly reliable.

(adapted from ProQuest Research Companion http://pqrc.proquest.com/learning_module/find_information/objective-3/feature-1132?type=transcript)