Perhaps you should try some spelling variations:
2.39 communication » 2.3 communication, 2.7 communication, 1.3 communication
technology u.s » technology uses, technology 2.2, technology use
u.s population » 2.1 population, 2.2 population, 2.3 population
population per » population panel, population p230, population area
4 development » 2 development, 4 developing
1 fabrique » la fabrique
fig 2.39 » fig 2.3, fig 2.30, fig 2.35
per fig » per firm
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 u.s population per fig 2.39 communication costs 4 development 1 fabrique.*.