Perhaps you should try some spelling variations:
6.2.4.1 communication » 6.2.4.2 communication, 6.2.4.3 communication, 11.4.1 communication
population panel » population age, population based, population area
technology than » technology tax, technology trap, technology change
than population » change population, orphan population, urban population
a developpement » au developpement, de developpement, le developpement
panel fig » panel firm, panel i, panel ii
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 than population panel fig 6.2.4.1 communication costs a developpement _ maurice.*.