Perhaps you should try some spelling variations:
"biological terrorism" » "biological theories"
"political theorists" » "political theories", "political theory", "political aphorisms", "political theoriess", "political theorys", "critical theorists"
"political theorist" » "political theories", "political theory", "critical theorist"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("political theorist") OR ("biological terrorism"))) OR ("political theorists")).
• Removing quotes may allow a broader search: (((( political theorist ) or ( biological terrorism ))) or ( political theorists )).
• Adding a wildcard symbol may retrieve word variants: (((("political theorist") or ("biological terrorism"))) or ("political theorists"))*.