Once you perform your search, you can sort the search results by Date, Title, ID, or Relevance by clicking on the respective tab on the top left under "Sort by:". The "Sort by:" option is available in the Index-Catalogue and eTkeVK2 tabs only. 

Dates in Index-Catalogue and eTkeVK2 can be displayed in ascending or descending order by clicking on the corresponding ▲ (ascending) or ▼ (descending) Date options.