You can group references by various criteria, for example, by keywords or by categories. If you select multiple criteria, the references will be grouped by the first criterion first, and then within that group, by the next criterion, and so on.
1.In the Table view on the toolbar, click Group.
2.To add a column for the grouping, under All columns select a field name from the list on the left and and then click Add.
3.To remove a criterion, select a field from Group by and click Remove.