Perhaps you should try some spelling variations:
german gender » german lander, germany under, german border
human gene » human genome, human gender, human bone
yang yang » wang yang, wang yan
congo can » congo call, cong van, congo a
cong seo » hong seo, cong shu, cong sun
yang yi » yang di, yang xi, yang jui
minh » mind, ming, mine

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

• Performing a fuzzy search may retrieve terms with similar spellings: yang yang yi ((human gene) or (german gender)) anh minh ((cong seo) or (congo can)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: yang yang yi ((human gene) OR (german gender)) anh minh ((cong seo) OR (congo can)) ;.
• Adding a wildcard symbol may retrieve word variants: yang yang yi ((human gene) or (german gender)) anh minh ((cong seo) or (congo can)) ;*.