Perhaps you should try some spelling variations:
su sach » so sach, vu sach
va tinh » may tinh
va dinh » van dinh, va kinh, vu dinh
cac duc » cac du, cao duc, cac dac
sach ty » sach y, sach tu, sach thu
qua cac » cua cac
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((nang xa) or (nang ma)) hoi. hieu qua cac duc ((va dinh) OR (va tinh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang xa) OR (nang ma)) hoi. hieu qua cac duc ((va dinh) OR (va tinh)) vi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang xa) or (nang ma)) hoi. hieu qua cac duc ((va dinh) OR (va tinh)) vi cua tre*".