Perhaps you should try some spelling variations:
"spectral types with belligerents" » "special types with belligerents", "several types with belligerents", "special type with belligerents"
"neutral types with belligerents" » "neutral type with belligerents", "neuronal types with belligerents", "several types with belligerents"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"neutral types with belligerents\") OR (\"spectral types with belligerents\"))".
• Removing quotes may allow a broader search: (( neutral types with belligerents ) OR ( spectral types with belligerents )).
• Adding a wildcard symbol may retrieve word variants: (("neutral types with belligerents") OR ("spectral types with belligerents"))*.