Perhaps you should try some spelling variations:
nhung xuong » nhung huong, nhung tuong, nhung phuong
hieu quang » thieu quang, hieu quan, hieu qua
thanh tung » thanh cong
hieu sang » chieu sang, hieu lang, nhieu tang
dan phan » doan phan, van phan, dam phan
dan chan » dan gian, dan ca, van chat
tung va » trung va, tuong va, dung va

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) OR (hieu quang)) - thanh tung va nhung xuong ((dan phan) or (dan chan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - thanh tung va nhung xuong ((dan phan) OR (dan chan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (hieu quang)) - thanh tung va nhung xuong ((dan phan) or (dan chan)) cau".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) OR (hieu quang)) - thanh tung va nhung xuong ((dan phan) or (dan chan)) cau*.