Perhaps you should try some spelling variations:
population census » population density, population densities
6.2 communication » 3.2 communication, 2.3 communication, 2.7 communication
technology meet » technology meets, technology mest, technology mmet
meet population » deer population, moment population, recent population
2.2 developing » 3.2 developing, 3.3 developing, 2.2 development
census dpc » census due
costs 2.2 » costs 4.2, costs 2.3, cost 2.2
dpc 6.2 » cdsc 6.2

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

• Adding a wildcard symbol may retrieve word variants: technology meet population census dpc 6.2 communication costs 2.2 developing _ african.*.