Perhaps you should try some spelling variations:
trinh phuong » trinh duong, trinh dung, trinh cong
phuong hai » phuong mai, phuong tai, phuong phap
quang tan » quang tuan, quang tran, quang toan
tan bien » tang bien, tai bien, ran bien
van hieu » cao hieu
hieu tra » dieu tra, hiep tran, chieu tro
hai tan » hai van, hai quan
bien so » bien doi
tan van » tran van, tang van, luan van

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh phuong hai tan bien so ) or ( tinh quang tan van hieu tra ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh phuong hai tan bien so ) OR ( tinh quang tan van hieu tra ))*.