Perhaps you should try some spelling variations:
2.3.1.1 communication » 2.2.5.4 communication, 3.4.1 communication, 6.2.4.1 communication
population panel » population age, population based, population area
developpement et » developpement des, developpement de, development east
technology trap » technology trade, technology tax, technology than
trap population » rural population, rapid population, boar population
4 developpement » de developpement, le developpement, et developpement
fig 2.3.1.1 » fig 2.3.1.2, fig 2.3.1.3, fig 2.3.1.4
et fabrice » avec fabrice, roth fabrice
panel fig » panel firm, panel i, panel ii
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 trap population panel fig 2.3.1.1 communication costs 4 developpement et fabrice.*.