Rule: Do not direct a reader to an outside source/website to learn more about a topic. Include all necessary information to cover your content from beginning to end within the content itself.
Correct Examples:
- 
According to Cancer.org, over 90 percent of adults are affected each year. 
 - 
Ask your doctor before starting any type of weight-loss or exercise regimen. 
In the case of precautionary or preventative measures, it is acceptable to direct the reader to ensure the information is applicable. - 
W3Schools provides comprehensive tutorials for beginners in Web design.
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Monster is a great avenue to find resources for job offerings.
 
Incorrect Examples:
- 
Visit Cancer.org for more information on how adults are affected each year.
 - 
Practice online with tutorials from W3Schools.com.
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Check out Monster.com and careerbuilder.com for job listings in your area.
 
Rule: If you use a website as a reference point, use the primary domain name (e.g. Indeed.com or CrowdSource.com) and not the entire URL (e.g. http://www.indeed.com/marketing-jobs).