Perhaps you should try some spelling variations:
scientific exploration » scientific explanation, scientific application, scientific collaboration
american voyages » american villages, aerial voyages, american images
african voyagers » african managers, african teenagers, african voices

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: european AND ((american voyages) OR (african voyagers)) of scientific exploration.
• Adding a wildcard symbol may retrieve word variants: european and ((american voyages) or (african voyagers)) of scientific exploration*.