Using Boolean search
Boolean searching allows you to combine up to three search terms.
For example: submitting a query for voyage will result in a search for
all works in the database in which that term occurs. If the term
gold was added using the AND operator to the previous example search,
the search would be limited to works in which both voyage
and gold appear somewhere in the text.
Precedence of Boolean operators
Boolean expressions are operated on from left to right. This means
that you will need to take some care in formulating your search.
For example: You wish to find any texts that mention the word tobacco
AND either the word Indian OR trade. Your search should be formulated as: Indian OR trade
Understanding the results
Since the search works from left to right, the search will first
look for the set of texts that contains EITHER trade or tobacco.
Then the search will look within that set of texts for the ones
that also mention tobacco. Those texts will be your results
If you had formulated your search as tobacco AND Indian OR trade
you would have gotten a very different set of results. Why?
Since the search works from left to right, the search would have
first looked for the set of texts that contains BOTH the words tobacco
and Indian. Next it would have looked for the texts that
contain the word trade. Then it would combine those two sets
of results and eliminated the duplicates to give you your results.
This means you would have a whole set of texts that contain trade
but make no mention of tobacco. You can also use the Boolean
NOT option look for occurrences where a term is used without
the presence of another term.
For example, a search for witch AND England NOT colony
will retrieve texts in which witches in England, not the colonies,