Perhaps you should try some spelling variations:
van thiet » va thiet, dan thiet, can thiet
hieu van » hieu va, thien van, lieu va
vu sach » vu bach, su sach, vu khach
nang co » nang cao, nang doc, nang noi
van hac » van hoc, van ha, van hai
tinh vi » trinh vi, tinh voi, tinh va
y nang » ky nang, ly nang, v nang
co hoi » co hoc, co loi
bac va » ban va, bac ha, tac va
bao va » bao ve, tao va, ban va

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach y nang co hoi. hieu van hac ((bac va) OR (bao va)) tinh vi van thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach y nang co hoi. hieu van hac ((bac va) OR (bao va)) tinh vi van thiet".
• Adding a wildcard symbol may retrieve word variants: vu sach y nang co hoi. hieu van hac ((bac va) OR (bao va)) tinh vi van thiet*.