Perhaps you should try some spelling variations:
communications costs » communication costs, communications _
volume ventilation » volume estimation, volume variation
technology volume » technologies volume, seismology volume, technology evolution
ventilation rules » ventilation modes, ventilation issues, regulation rules
developpement de » developpement des, developpement durable
4 developpement » de developpement, le developpement, et developpement
de afrique » de l'afrique, en afrique, l afrique
costs 4 » costs _, costs a, costs 4.2

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

• Adding a wildcard symbol may retrieve word variants: technology volume ventilation rules trade _ communications costs 4 developpement de afrique.*.