Perhaps you should try some spelling variations:
2.3.1.4 communication » 2.3.1.1 communication, 2.2.5.4 communication, 2.14 communication
population panel » population age, population based, population area
developpement du » developpement de, developpement des, developpement et
4 developpement » de developpement, le developpement, et developpement
technology tax » technology than, technology trap, technology tpm
tax population » farm population, fast population, boar population
fig 2.3.1.4 » fig 2.3.1.2, fig 2.3.1.3, fig 2.3.1.5
panel fig » panel firm, panel i, panel ii
costs 4 » costs _, costs a, costs 4.2
du face » dual face, buy face, der face

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

• Adding a wildcard symbol may retrieve word variants: technology tax population panel fig 2.3.1.4 communication costs 4 developpement du face.*.