Perhaps you should try some spelling variations:
verbal communication » nonverbal communication, virtual communication, oral communication
developing biogas » developing areas, developing global, developing cities
technologien ad » technologien am, technologien und, technologien als
ad information » d information, nd information, od information
7.3 developing » 3.3 developing, 1.3 developing, 2.2 developing
biogas african » baga african
3d verbal » 3 verbal, _ verbal, a verbal
costs 7.3 » costs 2.3, costs 4.3, costs 5.3

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

• Adding a wildcard symbol may retrieve word variants: technologien ad information _ 3d verbal communication costs 7.3 developing biogas african.*.