Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu tach » hieu cach, chiet tach, chieu sach
trinh vat » trinh van, trinh luat, sinh vat
doc hieu » toc thieu, hoc thieu, hoc hien
trinh vi » trinh va, trinh ve, trinh viet
cong tai » cong thai, cong tac, dong tai
tai phan » tai thanh, tai phong, tai ngan

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu tach - canh ((trinh vi) or (trinh vat)) thong cong tai phan tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu tach - canh ((trinh vi) OR (trinh vat)) thong cong tai phan tu.
• Adding a wildcard symbol may retrieve word variants: doc hieu tach - canh ((trinh vi) or (trinh vat)) thong cong tai phan tu*.