Perhaps you should try some spelling variations:
dau truc » cau truc, dai truc, doan truc
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
sach ky » sac ky, sach y, sach kem
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
va dau » va dao

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

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