Perhaps you should try some spelling variations:
6.1 communication » 4.1 communication, 1.1 communication, 3.1 communication
study population » student population, student populations, city population
developpement la » developpement de, developpement et, developpement du
population case » population based, population age, population change
4 developpement » de developpement, le developpement, et developpement
case france » trade france, marie france, state france
france 6.1 » france 1
la afrique » l afrique, la fabrique, en 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 study population case france 6.1 communication costs 4 developpement la afrique.*.