A succession of words does not make a request.

In order to define groups of documents, you need to group them by operator:

• "OR" for equivalent terms: result -> all documents containing at least one of the terms.
• "AND" for complementary terms: result -> documents which imperatively contain both terms.
• "NOT": result -> excludes documents which contain the excluded term.

There are other operators:

• right side truncation: it allows you to run a search on a root or to group all declensions of one word. For instance: The request fem* will group all documents containing the terms: female, feminine, femininity, feminists.
• proximity operators are used to define an element of proximity between two terms.
• search of the exact phrase or chain of character.

The way to phrase a request varies according to the engine used, each having their own syntax, their own control language.

Request example: energy use cars

• will bring no result on the Factiva database because all three terms energy use cars will be treated as a chain of characters.
• will bring over a million documents on Google because they will be treated as 3 terms linked by two Boolean "AND".

To find out the syntax of a database, you need to visit its "help" or "examples" page.

Some databases allow you to record simple requests and to then cross them using the session "history".