Boolean Search Operators

You can use the following Boolean search operators to define the relationships between your keywords and narrow or broaden your search results.

Operator	Example	Finds articles with...
AND	badgers AND tuberculosis	both the word badgers and the word tuberculosis
OR	badgers  AND  (tuberculosis OR TB)	either the word tuberculosis or the word TB and the word badgers
-	badgers AND Tuberculosis -vaccination	the words badgers, tuberculosis but not the word vaccination

Note: the hyphen (or minus) symbol is used as the NOT operator.

When you use multiple operators in your search, ScienceDirect applies them in this order:

1. NOT (-)
2. AND
3. OR

When your search query includes multiple Boolean operators, use brackets " ( )" to help the search engine group them in a way that is relevant for your research:

"badgers" OR "meles meles" AND tuberculosis finds all documents in which the phrase "meles meles" AND the word tuberculosis are both present as well as all documents in which the word badgers  is present.

 (badgers OR "meles meles") AND tuberculosis will only find documents that include the word tuberculosis in addition to either the word badgers  or the phrase "meles meles".

 

Searching for phrases/exact phrases

Use quotation marks around words to find documents where your search words appear together

•  "BCG-Vaccination" finds results with BCG-Vaccination and BCG Vaccination

To find results that contain your exact phrase, including punctuation, put curly brackets around your keywords.

• {BCG-vaccination} or {BCG vaccination} finds different results because the "-" is considered when it's inside the brackets.

 

Using wildcards

If you are not sure of a spelling you can use an asterisk (*) or question mark (?)

Use an asterisk (*) as a multi-character wildcard to replace characters anywhere in a word. 

• vaccin* will find vaccine, vaccinate, vaccination 
• behavi*r will find behaviour or behavior

Use a question mark to replace exactly one character in a word.  Use one question mark for each character you want to replace.

• infect?? finds infected but not infection

 

Special characters

• you can enter any UTF-8 character into the search form.
• To search for the chemical notation "H₂O," enter H2O.
• To search for the name Fürst, enter Fürst or Furst.
• To search the Greek letter Ω, enter omega. This matches documents containing the word omega as well as the symbols Ω (uppercase omega) and ω (lowercase omega).

 

Plurals of words

ScienceDirect automatically looks for the plural of most keywords

• method finds method and methods
• criterion finds criterion but not criteria

 

British vs American Spellings

ScienceDirect looks for both British and American spellings 

• colour also finds color
• fibre also finds fiber