Is not necessary to enter a value for each field in the search form. If you don't enter a value for a field all possible values for that field will be selected. If you do not enter any value in the form, all entries in the database will be selected.
In the fields author and title you can enter free text you want to search for.
With subject, ethnic group and region you can choose from a predefined range of values.
By entering a value in the year fields you can specify a range for the year of publication. Publications equal to or later than the start and equal to or earlier than the end will be selected. If you only specify the start of the range, every publication with a year of publication equal to or later then the start of the range will be selected. The same applies (vice versa) if only the end of the range is filled.
If a value has been entered/chosen for multiple fields you can implement AND/OR functionality between the fields by choosing a value for the and/or radio button preceding those fields. Choosing an option for an and/or button is only effective when a value has been entered for the field below that and/or button and then only when a value has been entered for at least two fields in the form.
