Perhaps you should try some spelling variations:
developing country » developing countries
country variables » control variables, country parable, country variance
information last » information list, information lost, information law
a communication » la communication, data communication, data communications
last decades » last decade, lost decade, past decade
4 developing » 3 developing
decades a » decades _, decade _, decade 1
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 _ information last decades a communication costs 4 developing country variables.*.