Perhaps you should try some spelling variations:
2.3.1.3 communication » 2.3.1.1 communication, 2.2.3 communication, 2.2.5.4 communication
population panel » population age, population based, population area
developpement de » developpement des, developpement durable
technology tax » technology than, technology trap, technology tpm
tax population » farm population, fast population, boar population
fig 2.3.1.3 » fig 2.3.1.2, fig 2.3.1.4, fig 2.3.1.5
de fabrice » die fabrics, avec fabrice, die fabriken
panel fig » panel firm, panel i, panel ii

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 2.3.1.3 communication costs _ developpement de fabrice.*.