How can you trust information you find on the Internet?  Where can you find an answer that is detailed enough to be useful, but not too complex for you to understand?  Since anyone can publish information instantly on the World Wide Web distinguishing quality information can be very difficult.  Before the coming of the information age, there were only a few options for research – books, magazines, and scholarly journals.

Scholarly journals (also called academic, peer-reviewed, or refereed journals) are the traditional method of communicating new scientific discoveries.  Authors generally submit their articles to several other scientists for review and comment, and these reviewers must approve the article before it is published.  Since the audience is other scientists, the language used is highly technical and specific to the field.  Scholarly journals are one type of primary source for research.

Primary sources are newly created or recorded knowledge by a scientist or researcher.  These can be scholarly journal articles, scientific reports or even an in-person presentation.  Secondary sources review, discuss, or analyze primary sources and are written later.  Some examples of secondary sources are encyclopedia articles, science news reports, and most books.

Both types of information sources may have citations, references to earlier research.  Citations in a primary source are an acknowledgement of previous research and give a link between earlier knowledge and the current study.  Citations in a secondary source indicate where the author got the information they used to write their review of the topic.

One example of a secondary source is the online encyclopedia, Wikipedia.  There are many entries on mathematical topics such as RSA Cryptography and Goldbach's Conjecture.  Each of these articles was written by many people, but they used primary sources to write it.  You can find the source material used to write these articles in the References section of the article (see: RSA Cryptosystem References).  For each of these reference you can ask 4 questions to determine the quality and usefulness of each source.

1. Authority – who is the author and what is their level of expertise
2. Audience – who is the article written for and at what level is the article written
3. Currency – how recent is the article and does that matter
4. Content – could you understand and use the article for a paper in this class

Let's take the second reference and evaluate it along our 4 criteria.

2. Rivest, R., A. Shamir, L. Adleman (1978). "A Method for Obtaining Digital Signatures and Public-Key Cryptosystems" 

1. Authority - Three researchers at the Massachusetts Institute of Technology (MIT), inventors of RSA encryption
    
2. Audience - Published in Communications of the ACM, a scholarly journal used to communicate with other scientists
    
3. Currency - almost 40 years old, but as the foundational paper it will always be important
    
4. Content - read the Abstract and Examples in the paper to see if you can understand the math