You can apply as many keywords as you want to each of your references.
Click the Context tab.
Method 1: Type the keywords directly into the
Keywords box.
Citavi will automatically complete the keyword you are typing using existing keywords in the project.
To accept a suggestion, press
→ Tab,
or
Enter. To reject the suggestion, continue typing the new keyword.
Method 2: Click the blue Keywords link, to display the keywords dialog box.
In the All keywords column, select the keyword(s) you want to apply and click Add.
Close the window by clicking OK.