Perhaps you should try some spelling variations:
population center » population census, population censuses, population change
2.3 communication » 3.2 communication, de communication, 4 communication
technology meet » technology meets, technology mest, technology mmet
meet population » deer population, moment population, recent population
4.2 developing » 2.2 developing, 3.2 developing, 4.1 developing
center spect » center agent, center crec, center dpc
spect 2.3 » aspects 2.3, aspect 2.2, aspect 2.1

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

• Adding a wildcard symbol may retrieve word variants: technology meet population center spect 2.3 communication costs 4.2 developing _ african.*.