Perhaps you should try some spelling variations:
2.2 communication » 2.3 communication, 3.2 communication, 2.7 communication
study population » student population, student populations, city population
population based » population age, simulation based, population data
developpement en » developpement et, developpement des, developpement de
4 developpement » de developpement, le developpement, et developpement
based frame » based free, based face, based facade
frame 2.2 » france 2.2, frame 12.1, frame 1.3
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 based frame 2.2 communication costs 4 developpement en afrique.*.