Boolean operators can expand or refine your search as follows:

AND - Using the operator AND in a phrase, e.g. war AND peace, limits the search to include references that contain both the words/phrases either side of the operand, in this case, the search retrieves records containing both the indexed words (war/peace).

OR - Using the operator OR in a phrase, e.g. war OR peace, expands the search to include references that contain either or both of the words/phrases either side of the operand. In this example the search retrieves records containing the word war, records containing the word peace, as well records containing both words i.e. war and peace.

AND NOT - Using the operator AND NOT in a phrase excludes any references that contain the words/phrases that follow that operand, e.g. war AND NOT military would retrieve records which exclude references to the military, military conflict and so on.

Wildcards - There are two types of wildcard. Use the '?' symbol to replace a single letter, e.g. enter 'wa?' into the search term to retrieve hits relating to war and wax. Use the '*' symbol to replace a single or string of letters, e.g. enter 'wa*' to retrieve hits relating to war, wax, water and so on.