Perhaps you should try some spelling variations:
communications costs » communication costs, communications _
technology center » technology centers, technology centered, technology centres
developpement en » developpement et, developpement des, developpement de
center notation » cipher notation, tensor notation, contents notation
notation rate » mutation rate, notation save, innovation rate
rate rate » rates rates, rate ratio, rate water

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

• Adding a wildcard symbol may retrieve word variants: technology center notation rate rate data communications costs _ developpement en afrique.*.