Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
xa danh » va danh, dia danh, nam danh
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
hieu he » hieu ve, hiem he, hieu le
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
he nam » ha nam, nghe nam

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