Perhaps you should try some spelling variations:
trinh han » trinh quan
doi hieu » doi chieu, doi hien, hoi hieu
doc hieu » toc thieu, hoc thieu, hoc hien
ban cong » bang cong, van cong, phan cong
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan tap » toan ban

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

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