You can search for any combination of words or an exact phrase.
Filters limit your search according to certain attributes of the Author (historical period, school of thought, nationality) or of the Title (date published, subject area, topic).
Authors: you could limit your search to all works by Australians who lived in the 19th Century, or to all those authors who were members of the Austrian School of Economics.
Titles: you could limit your search to all titles pubished in the 18th century in the subject area of history, or to all those titles in the topic of the French Revolution.
To show how the filters can help narrow your search, an unrestricted search for the word “Constantinople” produces over 1,600 results; filtering the search by author (e.g. 18th century Frenchmen) produces about 135 results; filtering the search by title (e.g. 19th century economics) produces about 120 results.