Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
trinh vat » trinh van, trinh luat, sinh vat
cong toan » cong tan, cong hoan, cong tuan
doi chiu » doi chieu, doi chi, hoi chiu
trinh va » trinh van, trinh ve, trinh vi
toan ban » van ban
ban tu » van tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi chiu trach - canh ((trinh va) or (trinh vat)) thong cong toan ban tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi chiu trach - canh ((trinh va) OR (trinh vat)) thong cong toan ban tu.
• Adding a wildcard symbol may retrieve word variants: doi chiu trach - canh ((trinh va) or (trinh vat)) thong cong toan ban tu*.