Perhaps you should try some spelling variations:
german gender » german lander, germany under, german border
human gender » bhutan gender, human gene, human genome
dong hoang » hong hong
ning zhong » funing zhong, xiang zhong, anming zhang
yang yang » wang yang, wang yan
wang ning » wang jing, wang liang, wang yang
zhong zhi » zhang zhi, hong ghi, zhong tai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((dong hoang) OR (yang yang)) das ((human gender) OR (german gender)) wang ning zhong zhi ;~.
• Adding a wildcard symbol may retrieve word variants: ((dong hoang) or (yang yang)) das ((human gender) or (german gender)) wang ning zhong zhi ;*.