Perhaps you should try some spelling variations:
chieu tinh » trieu tinh, lieu tinh, chau tinh
nhung cong » dung cong, thong cong, hang cong
hoc chieu » hoc thieu, ho chieu, hoc hien
tran tuan » tran xuan, tran quang, tran thanh
dung cua » dung luan, dung cho
tap toan » tap quan, bai toan
tap doan » tap quan

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc chieu tinh - hanh ((dung cua) or (tran tuan)) nhung cong ((tap toan) OR (tap doan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc chieu tinh - hanh ((dung cua) OR (tran tuan)) nhung cong ((tap toan) OR (tap doan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc chieu tinh - hanh ((dung cua) or (tran tuan)) nhung cong ((tap toan) OR (tap doan)) cau".
• Adding a wildcard symbol may retrieve word variants: hoc chieu tinh - hanh ((dung cua) or (tran tuan)) nhung cong ((tap toan) OR (tap doan)) cau*.