When searching in catalogs and databases:

• Be creative in the words you use; if one doesn't work, try something else. Think of words with related meaning, such as natural resource management or restoration or conservation. 
• Begin with keywords, and use the subjects found in the articles that come up to find more information
• Use quotation marks around phrases, so they won't be searched as individual words.
• Use advanced search features in catalogs and databases to limit by date, language, type of article, etc

Official version at the National Archives: http://www.archives.gov/exhibits/charters/constitution.html

Primary sources are the original, first-hand accounts of a subject or event. They can include letters, diaries, manuscripts, autobiographies, interviews, opinions, surveys, investigations, court testimony and depositions, government documents, and more.

Primary sources are characterized by their content, regardless of whether they are available in original format, in microfilm/microfiche, in digital format, or in published format.

For a more detailed explanation on how to locate and use primary sources, read this guide, Primary Sources on the Web: Finding, Evaluating, Using

OSU Libraries has several ways of accessing primary sources online. These are only a few.