Perhaps you should try some spelling variations:
studies der » studie der, studien der, studies das
3 studies » 2 studies
main hong » min hong, tan hong, tin hong
hong than » hong tan, long thanh, hong hai
yang yi » yang xi, yang jui
a main » 1 main, 2 main
der a » der _, der e

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((((yang yi) or (yang dean))) or (yang di))a 3 studies der a main hong than ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((yang yi) OR (yang dean))) OR (yang di))a 3 studies der a main hong than ;*.