Truncation (The Asterisk)
An Asterisk (*) at the end of a term will allow you to search for different forms of a word with what you enter as a base. For example:
will return Education, Educator, Educators, Educate, Educated
whereas 
will return just Education exactly as you type it in.
This is a very simple and effective way of broadening the number of results you get.
Phrase Searching (Quotation Marks)
Quotations marks (" ") will group words as a phrase, ensuring they appear next to each other in the record. For example:
will return only articles that use those terms right next to each other.
whereas 
will return articles that may mention Great in one part of the record and Depression in another part of the record.
Advice on Searching for Primary Sources
First, don't restrict yourself to library databases. Primary source collections are often found free online, depending on the subject you are researching.
Second, when you use library databases you will get limited results if you try to search for "primary sources" because the Library of Congress does not use that subject heading. If a "Primary Sources" category is not available (JSTOR provides one that is very useful!) Try searching these subject headings instead:
- sources
- personal narratives
- documents
- speeches
- memoirs or autobiographies
- diaries
- letters or correspondences
- oral histories
SOME ADVICE ON AUTOBIOGRAPHIES: You will get limited results searching for the word "autobiography" since the Library of Congress does not use that subject heading. Try searching for "biography" but then look to make sure that the author is also listed as a subject. That is your clue that the person is writing about him or herself, and that is a primary source.
DOCUMENTARY HISTORIES: There are collections of documents relating to various subjects, such as Agriculture in the United States: A Documentary History. Search WorldCat or IDS for these by typing your subject along with the phrase "documentary history" in quotes.
DOCUMENTARY FILMS: Be wary of "documentaries" (films) because sometimes they are primary sources but sometimes they provide analysis that is secondary.
PUBLICATION DATES: Be aware that publication dates can be misleading. A new edition of a book published in 1952 is still a primary source even though its publication date is 2009. Look for a books original publication date, which is usually listed as well.
