Perhaps you should try some spelling variations:
developing control » developing country, developed control, developing countriesl
de communication » mobile communication, online communication
control trials » control trial, controlled trials, control variables
information 2 » information 3
technology 1 » technology _
4 developing » 3 developing
decades de » decades _, decades a, decada de
2 decades » _ decades, 1 decades, _ decade's
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 1 information 2 decades de communication costs 4 developing control trials.*.