Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
va dauh » va danh, va doanh
sach ky » sac ky, sach y, sach ty
hieu ca » hieu cac, hieu cua, hieu va
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ca cau » cua cau, cac cau, can cau
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky ((nang xa) or (nang ma)) hoi. hieu ca cau truc ((va dauh) or (va dau)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang xa) OR (nang ma)) hoi. hieu ca cau truc ((va dauh) OR (va dau)) dai cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang xa) or (nang ma)) hoi. hieu ca cau truc ((va dauh) or (va dau)) dai cua tre*.