Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
cua trong » cua truong, cua trung, ca trong
qua trong » quan trong, qua trinh, qua song
thanh lap » thanh san, phan lap, thanh hai
hoc hieu » hoc thieu, hoc hien, doc hieu
cong tan » cong tac, cong san, cong thanh

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 - canh tranh ((cua trong) OR (qua trong)) ((cong dong) or (cong tan)) thanh lap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu quang - canh tranh ((cua trong) OR (qua trong)) ((cong dong) OR (cong tan)) thanh lap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu quang - canh tranh ((cua trong) OR (qua trong)) ((cong dong) or (cong tan)) thanh lap".
• Adding a wildcard symbol may retrieve word variants: hoc hieu quang - canh tranh ((cua trong) OR (qua trong)) ((cong dong) or (cong tan)) thanh lap*.