Perhaps you should try some spelling variations:
trinh duong » trinh dung, trinh phuong, dinh duong
tran phung » tran phuong, trang phung, tran hung
anh quang » anh xquang, anh quan, nhanh quang
chi tach » chiu trach, chiet tach, chi thanh
tap toan » tap quan, bai toan
tap doan » tap quan
doi chi » doi khi

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi chi tach - anh quang ((tran phung) or (trinh duong)) cong ((tap toan) OR (tap doan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi chi tach - anh quang ((tran phung) OR (trinh duong)) cong ((tap toan) OR (tap doan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi chi tach - anh quang ((tran phung) or (trinh duong)) cong ((tap toan) OR (tap doan)) cau".
• Adding a wildcard symbol may retrieve word variants: doi chi tach - anh quang ((tran phung) or (trinh duong)) cong ((tap toan) OR (tap doan)) cau*.