Perhaps you should try some spelling variations:
developing biogas » developing areas, developing global, developing cities
information age » information storage, information access, information about
3 communication » 4 communication, de communication, data communication
biogas african » baga african
technology 1 » technology _
age debatte » die debatte, die debatten, eine debatte
debatte 3 » debate 3, debatte a, debatte i

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

• Adding a wildcard symbol may retrieve word variants: technology 1 information age debatte 3 communication costs _ developing biogas african.*.