Perhaps you should try some spelling variations:
cell communication » cell communications, oral communication, verbal communication
developpement en » developpement et, developpement des, developpement de
variation using » variations during, variation und, variation among
deep cell » deep wells
a das » 2 das, 3 das, _ das
apologia » apologies, apology

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "apologia _ variation using deep cell communication ((a das) OR (1 das)) developpement en afrique.~".
• Adding a wildcard symbol may retrieve word variants: apologia _ variation using deep cell communication ((a das) OR (1 das)) developpement en afrique.*.