Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
kien cua » khien cua, dien cua, tien cua
doc sach » hoc sach, toc sach, nuoc sach
hieu va » hieu qua
sach ky » sac ky, sach y, sach ty
va dinh » van dinh, va kinh, va tinh
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ky nang xa hoi. ((hieu va) OR (lieu va)) tham thuc ((va dan) or (va dinh)) kien cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky nang xa hoi. ((hieu va) OR (lieu va)) tham thuc ((va dan) OR (va dinh)) kien cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky nang xa hoi. ((hieu va) OR (lieu va)) tham thuc ((va dan) or (va dinh)) kien cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach ky nang xa hoi. ((hieu va) OR (lieu va)) tham thuc ((va dan) or (va dinh)) kien cua tre*.