Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
trung phai » trung phan, trung phat, truong phan
nhung cong » dung cong, thong cong, hang cong
trung hai » trung ha, trung dai, trong hai
doi hieu » doi chieu, doc hieu, doi hien
cong tac » cong ty
tac than » tac thanh, tam than, tac nhan
than tap » toan tap, han tap, phan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi hieu quang - thanh ((trung phai) or (trung hai)) nhung cong tac than tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu quang - thanh ((trung phai) OR (trung hai)) nhung cong tac than tap.
• Adding a wildcard symbol may retrieve word variants: doi hieu quang - thanh ((trung phai) or (trung hai)) nhung cong tac than tap*.