Perhaps you should try some spelling variations:
population sector » population structure
5.2 communication » 3.2 communication, 6.2 communication, 2.2 communication
technology ties » technology tieups, technology studies, technology thesis
ties population » u.s population, les populations, nations population
sector process » sector prices, actor process, sector projects
process 5.2 » process 2.2, process 5.1, process 2.1
a afrique » l afrique, en afrique
costs a » costs _, costs 4

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

• Adding a wildcard symbol may retrieve word variants: technology ties population sector process 5.2 communication costs a development a afrique.*.