Perhaps you should try some spelling variations:
phuong bang » phuong hoang, phuong giang, phuong quang
phuong hang » phuong hoang, phuong hanh, phuong thanh
chieu sang » chieu sach, chieu xanh, hieu lang
tranh cua » doanh cua, manh cua
ho chieu » theo chieu, hoc thieu, doi chieu
bai toan » bai tap
va toan » van toan, tap toan, va thanh

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho chieu sang - canh tranh cua ((phuong hang) OR (phuong bang)) ((va toan) or (bai toan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho chieu sang - canh tranh cua ((phuong hang) OR (phuong bang)) ((va toan) OR (bai toan)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho chieu sang - canh tranh cua ((phuong hang) OR (phuong bang)) ((va toan) or (bai toan)) cao".
• Adding a wildcard symbol may retrieve word variants: ho chieu sang - canh tranh cua ((phuong hang) OR (phuong bang)) ((va toan) or (bai toan)) cao*.