Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
dinh cao » tinh cao, dinh cac, dinh dao
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
dinh co » dinh so, dinh cu, dinh bo
cua tre » cua te, cuu tre, cua triet

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 ky nang ((le hoi) or (ma hoa)). hieu va cac thuc va ((dinh co) OR (dinh cao)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((le hoi) OR (ma hoa)). hieu va cac thuc va ((dinh co) OR (dinh cao)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((le hoi) or (ma hoa)). hieu va cac thuc va ((dinh co) OR (dinh cao)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((le hoi) or (ma hoa)). hieu va cac thuc va ((dinh co) OR (dinh cao)) cua tre*.