Perhaps you should try some spelling variations:
phuong cong » phuong dong, phong cong, phung cong
hanh tang » hanh trang, anh tang, hanh mang
va phuong » va thuong, cac phuong
ho chieu » theo chieu, hoc thieu, doi chieu
tac toan » tam toan, hach toan, tich toan
tap toan » tap doan, tap quan, bai toan
tang va » trang va, tang van, thang va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((theo tieu) or (ho chieu)) xanh - hanh tang va phuong cong ((tac toan) OR (tap toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((theo tieu) OR (ho chieu)) xanh - hanh tang va phuong cong ((tac toan) OR (tap toan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((theo tieu) or (ho chieu)) xanh - hanh tang va phuong cong ((tac toan) OR (tap toan)) cau".
• Adding a wildcard symbol may retrieve word variants: ((theo tieu) or (ho chieu)) xanh - hanh tang va phuong cong ((tac toan) OR (tap toan)) cau*.