When information need is more complicated and/or we are seeking for records with keywords in particular fields (e.g. Authors or ISSN), the Advanced search is a good choice. It is wise to empty the Keywords search window with the [Clear] button first.

The information need expressed in the example on Figure 3 was about legislation of abortion. The user was aware of the fact that both concepts could be expressed with more than one keyword. The user was also certain that the document he was looking for was published in year 2000.

With Advanced search the user can define keywords, choose fields in which search should operate and use logical operators by placing keywords inside the row or by selecting operators from combo list. Problems with priority of operators are diminished with parentheses around the predefined cells for OR-ed keywords. If more than one keyword is entered inside the same cell this is treated as a phrase (see "abortion, legal" on the Figure 3).

Figure 3: Building and interpretation of an advanced query.

It is possible that three rows of keyword cells are not enough. With the Add row / Remove row buttons the number of rows and length of the query could be adapted.

Clear advanced query link empties the Advanced query cells and prepares search engine for further work.