Perhaps you should try some spelling variations:
"slave trade / west indien, british" » "slave trade / west indies, british", "slave trade / west indian, british", "slave trade / west indians, british"
"slave trade / east indies, british" » "slave trade / east india, british", "slave trade / west indies, british"

Try widening your search to All Fields.

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: (("slave trade / west indien, british") OR ("slave trade / east indies, british")).
• Removing quotes may allow a broader search: (( slave trade / west indien, british ) or ( slave trade / east indies, british )).
• Adding a wildcard symbol may retrieve word variants: (("slave trade / west indien, british") or ("slave trade / east indies, british"))*.