Perhaps you should try some spelling variations:
11.6 communication » 1.1 communication, 1.3 communication, 1.4 communication
seismology volume » technology volume
volume variation » volume evaluation, volume ventilation, volume estimation
variation system » valuation system, evaluation system, irrigation system
au developpement » du developpement, de developpement, le developpement
developpement la » developpement de, developpement et, developpement du
system threats » systems threats, system trends
threats 11.6 » threats 10.5, threats 12.1, threats 12.2
la afrique » l afrique, la fabrique, en afrique

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

• Adding a wildcard symbol may retrieve word variants: seismology volume variation system threats 11.6 communication _ au developpement la afrique.*.