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You may use the "Start date" and/or "End date" boxes to set a range for the date shown by the maps searched for. Years A.D. should be given as positive numbers, e.g.1453; years B.C. should be given as negative numbers, e.g.-753;
In the indexed search box, select one or more words and phrases, to
do an indexed search for them. Use the control key to select more than one.
Here is a complete list of the search
terms: it is of little interest to human readers.
As well as, or instead of, selecting terms from the list box for an indexed search, you may type one or more words, separated by commas, into the free search box. This search will be more exhaustive but slower. In a free search, words searched for are treated separately, and words of fewer than four letters are ignored; so "age of discovery" is treated as "discovery".