Perhaps you should try some spelling variations:
phuong thuat » phuong thuc, phuong thao, phuong thu
thuong thuat » thuong thuyet, thuong thuc, trong thuat
hieu lang » chieu sang, hieu quang, nhieu tang
ung cuong » hung cuong, quang cuong, tang cuong
hoc hieu » hoc thieu, hoc hien, doc hieu
dan than » ban than, van than, dan toan
dan chan » dan gian, dan ca, van chat

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu lang - thanh ((phuong thuat) OR (thuong thuat)) ung cuong ((dan than) or (dan chan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - thanh ((phuong thuat) OR (thuong thuat)) ung cuong ((dan than) OR (dan chan)) cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - thanh ((phuong thuat) OR (thuong thuat)) ung cuong ((dan than) or (dan chan)) cau*".