Using Boolean Operators (AND, OR, and NOT)
Learning to use Boolean Operators between your key words or phrases can greatly enhance the quality , quantity, and specificity of the information you find. Boolean and other logical operators act as signals to search engines and other databases to connect your key words in specific ways. By using them, you get more control over the content of the articles that will come back to you, as well as the number of articles that will come back.
The AND Operator Connect your search words with the operator AND to indicate to the search engine or database that you want all articles that come up to contain all of the search words. This has the effect of narrowing your search.
So the search term "fishing AND Minnesota" should return only articles that concern both Minnesota and fishing.
So "world bank AND India" when you are interested only in how the World Bank operates in India.
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Operator
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Search Phrase
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Effect
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Search Diagram
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AND
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"media AND violence"
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Narrows your search so that only articles containing both search terms come back to you. Limits search results.
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(Here one circle stands for all the articles about media and the other for all the articles about violence; the red portion indicates what you get back from the search.)
The OR Operator Connect your search terms with OR to indicate that the articles that come back should contain at least one of your terms and may include both. This has the effect of broadening your search.
In "women OR females" articles could come back that mention only women or only females or both.
Use "teenagers OR young adults" when either term will do.
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Operator
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Search Phrase
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Effect
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Diagram
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OR
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"doctors OR physicians"
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Broadens your search so that all articles containing the word "doctors," as well as all articles containing the word "physicians," come back to you. Broadens search.
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(Here one circle stands for all the articles about "doctors" and the other for all the articles that mention"physians"; the red portion indicates what you get back from the search.)
The Not Operator Use the operator AND NOT or NOT to exclude terms from your search results.
So "apples AND NOT computers" when you are interested in apples you can eat.
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Operator
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Search Phrase
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Effect
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Search Diagram
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Not
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"computer networks NOT wireless"
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Brings back articles about wired networks and none that are about wireless networks. Limits search resutls.
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(Here one circle stands for all the articles about computer networks and the other for all the articles about wireless computer networks; the red portion indicates what you get back from the search.)
Nesting: Use Operators in Combination
"(dogs OR canines) AND heart worm"
"(computers AND Apple) AND NOT software"
"(movies OR television) AND children AND violence "
For a more thorough explanation of operators and how to use them, check out this web site from the University of Albany libraries.
Remember that each database or search engine is different. Some may allow you to use operators, some will ignore them. It is best to check the Help screens to see what operators, if any, will be allowed.
Truncation & Wildcards
Use truncation when you want to search for all words that share the same root.
So, when you use the asterisk* symbol to signal truncation, the search term instruction* brings back not only records that include the term instruction, but also records with instructions and instructional. Alien* searches for alien, aliens, alienated, alienation, and alienist.
Use wildcards when you want to replace unknown letters/characters in a term. Wildcards are useful when you are not sure how to spell a word, when there are alternative spellings of the word, or when you know only part of a term.
So for example, when the question mark (?) is a wildcard symbol, you can use it if you are unsure how to spell the word relevant: relev?nt.
Use it when you are looking for both woman and women: wom?n.
Defen?e will bring up both defense and defence (the British spelling). See the chart below for more examples.
Truncation and Wildcard Symbols by Database
Most databases allow you to use truncation and wildcards so that you can find various forms of words or unknown characters within words. However, each database has its own rules for which symbols to use. Online help within each database will give you the information you need to make use of these symbols. Consult the chart below for an introduction to using truncation and wildcards in the St. Mary's databases.
MnPALS
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Symbol
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Usage
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Examples
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? or *
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Stands for any number of characters, useful for finding all the words with the same root. Use at the end, middle, or beginning of a search term |
theat* finds theater, theatre, theaters, theatrical, etc. /?ology will retrieve anthropology, archaeology, psychology, etc |
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!
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Replaces a single unknown character |
wom!n finds woman or women |
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#
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Finds varient spellings in cases where one version of the word has one more character than another version |
colo#r finds color and colour, arch#ology finds archaeology and archeology |
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%
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Place the % sign followed by a number between two words to indicate that the words should appear within a particular distance from each other |
england%3ballads will retrieve Ballads of England, Ballads of Merry Olde England and England and Her Ballads
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ATLA/S, EBSCO, CPLI, ProQuest
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Symbol
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Usage
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Examples
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*
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Stands for any number of characters, useful for finding all the words with the same root |
educat* finds educator, educated, education, educate |
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?
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Use in place of characters in your search term, one for each character |
educat?? finds educator and educate but not education, wom?n finds woman or women |
InfoTrac, MLA International Bibliography
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Symbol
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Usage
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Examples
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*
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Stands for any number of characters, useful for finding all the words with the same root |
theat* finds theater, theatre, theaters, theatrical, etc. |
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?
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Stands for exactly one character and is useful if you are unsure of a spelling or if there are multiple spellings |
relev?nce if you can't remember whether it is ance or ence. Psych????y finds psychology or psychiatry but not psychotherapy. Defen?e finds both defense or defence |
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!
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Stands for one or no characters, useful when you want to match the singular and plural of a word but no other forms |
product! finds product and products but not productivity or production |
MNLink
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Symbol
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Uses
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Examples
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*
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Stands for any number of characters, useful for finding all the words with the same root |
instruction* finds instructions, instructional, instructing, etc. |
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#
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Represents a single character |
wom#n finds woman and women |
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?
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Represents any number of characters within a single term |
colo?r finds color, colour, colonizer, and colorimeter |
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?/N
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Include a number if you know the maximum number of characters that the ? will represent |
colo?1r finds color and colour but not colonizer and colorimeter |
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+
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Searches for a word and its plural form |
giraffe+ finds giraffe and giraffes |
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Symbol
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Usage
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Examples
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*
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Stands for any number of characters, useful for finding all the words with the same root |
cancer* finds cancer, cancers, cancerous |
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Use of the * symbol turns off automatic term mapping and automatic explosion of a MeSH term |
heart attack* will not find myocardial infarction |
JSTOR
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Symbol
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Usage
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Example
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+
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Finds s and es plurals/ does not find foreign language plurals. No other truncation devices supported. |
knife+ finds knife or knives, bus+ finds bus or buses |
ProjectMuse
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Symbol
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Usage
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Examples
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*
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Stands for any number of characters, useful for finding all the words with the same root |
modern* finds modern, modernity, modernism |
ScienceDirect
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Symbol
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Usage
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Examples
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!
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Stands for any number of characters, useful for finding all the words with the same root |
behav! finds behave, behavior, behaviorism |
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*
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Replaces a single unknown character except the first |
wom*n finds woman, women |
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