Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
tinh va » tich va, trinh van, trinh vat
tinh ca » tinh cao, tinh cua, tinh da
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
qua cac » cua cac
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
me hoi » le hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang ((me hoi) or (ma hoa)). hieu qua cac thuc va ((tinh ca) OR (tinh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((me hoi) OR (ma hoa)). hieu qua cac thuc va ((tinh ca) OR (tinh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((me hoi) or (ma hoa)). hieu qua cac thuc va ((tinh ca) OR (tinh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((me hoi) or (ma hoa)). hieu qua cac thuc va ((tinh ca) OR (tinh va)) cua tre*.