Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
chieu tinh » trieu tinh, lieu tinh, chau tinh
hanh tranh » canh tranh, hanh trinh, hanh trang
hieu quan » hieu qua, lieu quan, thien quan
tranh cua » doanh cua, manh cua
dung cong » dung trong
cong vang » cong lang, cong quang, cong ngang
vang toan » van toan, dang toan, quang toan
cua dung » cua dang, cua dong, qua dung
toan ban » van ban

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

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