Perhaps you should try some spelling variations:
china communications » china communication, china's communications, chile communications
trade development » software development
communications a » communications _, communications law, communications media
de variation » der variation, die variation, does variation
theorie de » theorie der, theorie des, theorie die
6 how » _ how, 3 how, 4 how
2 how » _ how

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "theorie de variation ((6 how) OR (2 how)) china communications a trade development 1 africa.~".
• Adding a wildcard symbol may retrieve word variants: theorie de variation ((6 how) OR (2 how)) china communications a trade development 1 africa.*.