Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
tran xuan » tran van
doi hieu » doi chieu, doc hieu, doi hien
cong tan » cong tac, cong san, cong thanh
ban can » ban dan, ban hang, ban hanh
van cau » van dau, van hau, van chat

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 lang - hanh ((tran xuan) or (tran quang)) thong cong tan ((ban can) or (van cau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi hieu lang - hanh ((tran xuan) OR (tran quang)) thong cong tan ((ban can) OR (van cau)).
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - hanh ((tran xuan) or (tran quang)) thong cong tan ((ban can) or (van cau))*.